InGaAs/InP Focal Plane Array (FPA) photodetector, which responses from 400nm-1700nm, is widely used in many applications, while its quantum efficiency in visible spectrum is commonly lower than Shortwave Infrared (SWIR) spectrum. In order to improve the quantum efficiency in visible spectrum, new methods need to be applied. Based on Mie scattering, sub-wavelength nanostructure arrays have been demonstrated that can be used as anti-reflecting mechanism in visible spectrum. Here we present the design and simulation of the parameters of nanostructure arrays, which aims at suppressing the reflection in visible spectrum, thus the transmittance of visible light from the back-illuminated side gets improved. Simulation results prove that designed nanostructure arrays can decrease the reflectance in visible spectrum, and integrating designed nanostructure arrays on ultra-thin back-illuminated layer can improve the transmittance, which improves the quantum efficiency of photodetector.
III-V compound semiconductors have abundant features for various electronic, optoelectronic and photonic applications, all arise from variform magic combination of group III and group V elements formed binaries, resulting in ever-changing characteristics. In this paper, diversified ternaries, quaternaries and quinaries are presented geometrically based on the binaries of arsenide, phosphide and antimonide, mainly concerned of their bandgap, lattice constant and the lattice match domain on different substrates. The features of nitride and dilute nitride, bismide and dilute bismuth, as well as boride, are also discussed briefly. An overall observation of whole III-Vs may contribute to the comprehensive understanding of their latent capacity and sustainable development, along with many challenges.
Highly uniform ball-shaped indium bump arrays with small pixel pitches down to 10 μm have been fabricated. Multilayer stacked metal contact electrodes covered by a thin SiNx dielectric layer serve as the under bump metallization. Indium bumps were thermally evaporated inside the SiNx openings on top of the electrodes. Wet lift-off of the indium bumps was achieved by using a negative photoresist with precisely controlled undercuts. By comparison to a recipe without the SiNx, the non-uniform reflow effect of the indium materials was effectively eliminated after the thermal treatment. A mean indium ball diameter of 6.05 μm with a small coefficient of variation of 2.6% was finally realized for 10 μm pitch arrays. These results demonstrate the fabrication method is promising to ensure a reliable flip-chip hybridization of ultra-fine pitch focal plane arrays to silicon readout circuits with high yield.
In order to study the effect of different passivation films on the detector performance, the front-illuminated planar-type 256×1 element InGaAs/InP detectors were fabricated with SiNx film and SiO2 film. The SiNx film was deposited by plasma enhanced chemical vapor deposition (PECVD) and SiO2 film was deposited by magnetron sputtering technology. The electrical properties and photoresponse characteristics were investigated after the detector mounted on dewar. The photoresponse maps from laser beam induced current (LBIC) method show that the isolation of adjacent elements of the detector with SiNx film is better than the detector with SiO2 film. Furthermore, at room temperature the average density of dark current and the average peak detectivity of the two kinds of detector is 26.8 nA/cm2 and 41.2 nA/cm2 at 100 mV reverse bias, 1.21×1012 cm·Hz1/2/W and 1.08×1012 cm·Hz1/2/W respectively. Therefore, the detector with SiNx film deposited by PECVD could availably passivate the surface in comparison with the detector with SiO2 film by magnetron sputtering technology.
This work is aimed at designing an optical nano-antenna structure to enhance the optical absorption in 1.0−1.7 μm and improve the performance of InP-based InGaAs sensors. We report comprehensive analysis of an optical nano-antenna structure of metallic ball array for surface plasmon enhancement of near-infrared photodetection. The enhancement capability of metallic ball array on InP substrate with periodicity in the range of 600−1200 nm and diameters in the range 100−300nm has been studied by theoretical modeling with a finite-difference time-domain(FDTD) method. Our simulation results show that the highest transmission efficiency is achieved when the diameter of the ball is around and the optimized periodicity of the ball array is around 800nm. After comparing the transmission spectra of the arrays made of different metals, silver is found to be the best. Because of the speciality of SPP modes, the enhancement relative to wavelengths near 1.1μm is obviously weaker than that near longer wavelengths. Coating a SiO2 film about 500nm over the arrays is found to be an effective solution to achieve higher transmission efficiency around 1.1μm.
The extended InGaAs short wavelength infrared (SWIR) detector covers 1.0-2.5 μm wavelength, which plays an important role in weather forecast, resource observation, low light level systems, and astronomical observation and so on. In order to fabricate the high performance extended InGaAs detector, materials structure and parameters were characterized with Scanning Capacitance Microscopy (SCM), Scanning Spreading Resistance Microscopy (SSRM), the spreading of minority carriers and lattice quality were obtained. Mesa etching process, etching damage restoration technique and low temperature passivation technique were used in the fabrication of the extended InGaAs detector. The improvement of material structure and device process was studied by fabricating and measuring different perimeter-to-area (P/A) photodiodes and singledevice, respectively. The dark current density of the extended InGaAs detector obviously was reduced, about 2 nA/cm2 at 170 K. The 512×256 FPAs were fabricated, the peak detectivity and the quantum efficiency of which are 5×1011 cmHz1/2/W and 80%, respectively. The staring image yielded of the 512×256 FPAs is shown, which demonstrates very good imaging quality.
The spectral irradiance of moonlight and air glow is mainly in the wavelength region from visible to short-wave infrared (SWIR) band. The imaging over the wavelength range of visible to SWIR is of great significance for applications such as civil safety, night vision, and agricultural sorting. In this paper, 640×512 visible-SWIR InGaAs focal plane arrays (FPAs) were studied for night vision and SWIR imaging. A special epitaxial wafer structure with etch-stop layer was designed and developed. Planar-type 640×512 InGaAs detector arrays were fabricated. The photosensitive arrays were bonded with readout circuit through Indium bumps by flip-chip process. Then, the InP substrate was removed by mechanical thinning and chemical wet etching. The visible irradiance can reach InGaAs absorption layer and then to be detected. As a result, the detection spectrum of the InGaAs FPAs has been extended toward visible spectrum from 0.5μm to 1.7μm. The quantum efficiency is approximately 15% at 0.5μm, 30% at 0.7μm, 50% at 0.8μm, 90% at 1.55μm. The average peak detectivity is higher than 2×1012 cm·Hz1/2/W at room temperature with an integrated time of 10 ms. The Visible-SWIR InGaAs FPAs were applied to an imaging system for SWIR and visible light imaging.
Reflow soldering is the primary method for Flip-chip bonding without high bonding pressure. Reflow process during
flip-chip technology in short wavelength infrared (SWIR) InGaAs/InP Focal Plane array (FPA) with indium solder was
studied in this paper. In order to analyze the formation of Indium oxide and its effects on Indium bump reflow process.
Indium bumps were investigated by X-ray Photoelectron Spectroscopy (XPS). The profiles of Indium bumps after reflow
were observed by scanning electron microscopy (SEM). The interaction between Indium and the metal in under bump
metallization (UBM) during reflow process was discussed. The current–voltage (I–V) curves of InGaAs/InP photodiodes
were measured before and after the reflow process. The dark current density at 0.1 V reverse bias of InGaAs/InP
photodiodes were studied. It was confirmed that the characteristics of InGaAs photodetectors haven’t degenerated after
reflow in this paper.
KEYWORDS: Indium gallium arsenide, Photodiodes, Modulation transfer functions, Sensors, Staring arrays, Diffusion, Near infrared, Absorption, Back illuminated sensors, Signal detection
Crosstalk characteristics of high density FPA detectors attract widespread attention in the application of electro-optical
systems. Crosstalk characteristics of near-infrared (NIR) InGaAs photodiodes and focal plane arrays (FPAs) were
studied in this paper. The mesa type detector was investigated by using laser beam induced current technique (LBIC) to
measure the absorption outside the designed photosensitive area, and the results show that the excess absorption enlarges
the crosstalk of the adjacent pixels. The structure optimization using the effective absorption layer between the pixels
can effectively reduce the crosstalk to 2.5%. The major crosstalk components of the optimization photodiode come from
the electronic signal caused by carrier lateral diffusion. For the planar type detectors, test structures were used to
compare the crosstalk of different structures, and the guard ring structure shows good suppression of the crosstalk. Then
the back-illuminated 32x32 InGaAs photodiodes with 30μm pitch were designed, and LBIC was used to measure its
lateral diffusion of the effective carriers and fill factor of photosensitive area. The results indicate that the fill factor of
detectors can reach up to 98% when the diffusion region is optimized, and the minimum response exists between two
neighborhood pixels. Based on these crosstalk measurement results and optimizing structure designs, the linear InGaAs
photodiodes were designed and thus the InGaAs FPA assembly was fabricated. The assembly shows higher
electro-optical performance and good improvement on crosstalk. The assembly was applied in infrared imaging system
and modulation transfer function (MTF) of FPA assembly was calculated to be above 0.50. The clear image based on
FPA assembly was obtained.
InxGa1-xAs ternary compound is suitable for detection in the shortwave infrared (1-3μm) band. The alloy In0.53Ga0.47As is lattice-matched to InP substrate and has a wavelength response between 0.9μm to 1.7μm at room temperature. The increase of indium composition can extend the wavelength response to longer infrared wave. With the Indium content 0.83, the cutoff wavelength can be extended to 2.6μm. In this paper, we reported the performance of 64x64 pixels mesa-type back-illuminated extended wavelength InGaAs detector arrays. The mesa type detectors were fabricated by ICP etching, side-wall and surface passivation by ICPCVD (inductively coupled plasma chemical vapor deposition) based on the MBE-grown p-i-n In0.83Al0.17As/In0.83Ga0.17As/InxAl1-xAs/InP epitaxial materials. The I-V characteristics and electro-optical performances of these detectors at different temperatures were measured, and the properties such as dark current, response spectra, responsivity, detectivity were analyzed. The results indicate that the dark current of In0.83Ga0.17As photodiodes decreases with decreasing temperature, varying from 4×10-4A/cm2 at 290K to 1.7×10-8A/cm2 at 180K. The spectral response showed slightly blue shift while the detectors were cooling down, and the cut-off wavelength is 2.57μm at room temperature and 2.43μm at 200K, respectively. The dark current density is 115nA/cm2 at 200K and -10mV bias voltage. The peak detectivity is 6.08E11cmHz1/2W-1.
In this paper, we focus on the influence of thermal treatment on the passivation of silicon nitride (SiNx) film of p-i-n InGaAs detector. In our experiment, the perimeter/area (P/A) test diodes are fabricated by using two different device processes, and the relationship between the dark current density and P/A is investigated. The results indicate that the thermal treatment in the vacuum can be able to improve the passivation SiNx film effect and thus suppress the perimeterrelated current with the decrease of two orders of magnitude. Then the analysis of dark current source is carried out. The result shows that the sample with SiNx film through thermal treatment is composed of diffusion current and ohmic current, on the contrary, the other mainly consists of surface leakage current and diffusion current. It is illustrated that the passivation effect of SiNx was strengthened after thermal treatment and surface leakage current can be suppressed.
Extended wavelength InGaAs photodiodes in 1.0~2.5μm spectral rang based on two types of material structures were investigated systematically. The first type InGaAs photodiode, marked by sample 1#, was fabricated using MOCVD epitaxial materials with P-i-N structure. The second type InGaAs photodiodes, marked by sample 2#, was fabricated using MBE epitaxial materials with P-i-N structure. The two types of photodiodes were fabricated by mesa etching technique, side-wall and surface passivation film. Dark current and voltage curves were measured by semiconductor parameters analyzer at different temperature, and dark current characteristics were analyzed using different perimeter to area method. The mechanism of the devices has been analysed. Polarization microscopy and conductive atomic force microscopy (c-AFM) have been used to investigate the local conductivity of the photodiodes’ sensitive area. Combining the optical and c-AFM micrographs with dark current characteristics, we intended to characterize the relationships of the leak current and the defect. The results indicate that sample 1# has relative much more leak defects than that of sample 2#, and thus the dark current sample 1# is higher than that of sample 2# and. The defects are generated at the body of material and spread to the surface, and these defects cause very high dark current of sample 1#.
The design of input stage amplifier becomes more and more difficult as the expansion of format arrays and reduction of
pixel size. A design method of low-offset amplifier based on 0.18-μm process used in small-size pixel is analyzed in
order to decrease the dark signal of extended wavelength InGaAs infrared focal plane arrays (IRFPA). Based on an
example of a cascode operational amplifier (op-amp), the relationship between input offset voltage and size of each
transistor is discussed through theoretical analysis and Monte Carlo simulation. The results indicate that input transistors
and load transistors have great influence on the input offset voltage while common-gate transistors are negligible.
Furthermore, the offset voltage begins to increase slightly when the width and length of transistors decrease along with
the diminution of pixel size, and raises rapidly when the size is smaller than a proximate threshold value. The offset
voltage of preamplifiers with differential architecture and single-shared architecture in small pitch pixel are studied.
After optimization under same conditions, simulation results show that single-shared architecture has smaller offset
voltage than differential architecture.
It is well known that In0.53Ga0.47As epitaxial material is lattice-matched to InP substrate corresponding to the wavelength from 0.9μm to 1.7μm, which results to high quality material and good device characteristics at room temperature. In order to develop the near infrared multi-spectral imaging, 512×128 pixels InGaAs Near Infrared Focal Plane Arrays (FPAs) were studied. The n-InP/i-InGaAs/n-InP double hereto-structure epitaxial material was grown by MBE. The 512×128 back-illuminated planar InGaAs detector arrays were fabricated, including the improvement of passivation film, by grooving the diffusion masking layer, the P type electrode layer, In bump condition and so on. The photo-sensitive region has the diffusion area of 23×23μm2 and pixel pitch of 30×30μm2 . The 512×128 detector arrays were individually hybridized on readout integrated circuit(ROIC) by Indium bump based on flip-chip process to make focal plane arrays (FPAs). The ROIC is based on a capacitive trans-impedance amplifier with correlated double sampling and integrated while readout (IWR) mode with high readout velocity of every pixel resulting in low readout noise and high frame frequency. The average peak detectivity and the response non-uniformity of the FPAs are 1.63×1012 cmHz1/2/W and 5.9%, respectively. The power dissipation and frame frequency of the FPAs are about 180mW and 400Hz, respectively.
InGaAs ternary compound is suitable for detector applications in the shortwave infrared (SWIR) band. Due to the advantages of good stability, low cooling requirements and high detectivity, InGaAs detectors have been applied widely in the space remote sensing area. However, InGaAs detectors would be affected by strong sunlight direct irradiation in space application. In this paper, a mesa-type InGaAs detector with large sensitive area of diameter 5mm was designed based on InP/In0.53Ga0.47As/InP epitaxial material, which is lattice-matched to InP substrate. The InGaAs detectors were fabricated by ICP etching, and packaged in a Kovar shell. The relative spectral response is in the range of 0.9μm to 1.7μm. The mechanism of the sunlight direct irradiation on InGaAs detector performance was studied. The sunlight were focalized by lens and irradiated directly on the detector. A piece of epitaxial material was investigated at the same time which was cleaved from a 2 inch wafer, same to the detector material. The real time testing was taken out to observe the output signal of the detector. After the irradiation experiment, the I-V curves and the relative response were tested immediately. The dark current of the detector increased temporarily, but come back to the original level after 24 hours. The response spectrum was nearly not affected. The XRD testing of the epitaxial material sample was carried out before and after sunlight direct irradiation. The sunlight irradiation causes thermal stress degradation. The thermal electrons were produced by the absorption of a great deal of visible light, leading to local enhancement of temperature and the lattice degeneration of the material.
The single-pixel extended wavelength mesa InGaAs/InAsP SWIR detector was reported. The properties of the detector were characterized and analyzed at 160K~300K. At the operating temperature of 200K , the dark current density is 1.37×104 nA/cm2(@-10mV), the cut-off wavelength is 2.43μm, the peak detectivity and the peak responsivity are 3.44×1011cmHz1/2W-1 and 1.41A/W, respectively. Through analysis of the dark current source, the analysis of reverse dark current indicates that the tunneling current plays an important role at high voltage or relatively low temperature, and at near room temperature and low bias voltage, the generation-recombination current is the main current source instead of ohmic current based on thermal activation energy approximate to Eg/2 and the bias-voltage characteristic of the first order derivative of dark current, while the zero-voltage current mainly consists of the interface current and the thermal background current.
Nanowire grating is designed within the wavelength range from 1μm to 3μm according to the sensitive wavelength of InGaAs short wave infrared (SWIR) detector. The polarization performance is analyzed on the basis of finite difference time domain (FDTD) method. In order to improve the polarization performance, we insert a SiO2 dielectric grating between metal grating and substrate to form Au-SiO2 hybrid grating. The numerical study shows transmittance of hybrid grating is almost 88%which is 18% higher than monolayer metal grating at 1.8μm. In addition, the hybrid grating with the grooved- SiO2 layer has higher transmittance efficiency than those with smooth SiO2 layer for special wave band. By optimizing the specific parameters of the hybrid grating such as period, thickness and the groove depth of SiO2, finally we obtain the optimal parameters of the designed hybrid grating: the grating period is 0.4 μm, the thickness and groove depth of SiO2 are 0.4μm and 0.1μm respectively. Numerical study shows that the designed grating has advantages of wide band, high transmittance efficiency and high extinction ratio.
Extended wavelength InGaAs infrared detector arrays in 1.0~2.5μm spectral rang based on three types of material structures grown by MBE were studied. The first type InGaAs detectors, marked by sample 1#, were fabricated using Pi- N epitaxial materials, mesa etching technique, side-wall and surface passivating film. The second type InGaAs detectors, marked by sample 2#, were fabricated using N-i-P epitaxial materials, mesa etching technique, side-wall and surface passivating film. The third type InGaAs detectors, marked by sample 3#, were fabricated using n-i-n epitaxial materials, planar diffusion process and surface passivating coating. I-V curves, low frequency noise and response spectra of these detectors were measured at the different temperature. The response spectra of these detectors cover 1.0~2.5μm wavelength range. The dark current density of three types InGaAs detectors are 28nA/cm2, 2μA/cm2, 9μA/cm2 at 200K and -10mV bias voltage, respectively. Compared to Sample 2# and Sample 3#, sample 1# presents the lower dark current at the same temperature and the same bias voltage, which mainly results in the improvement of surface passivation film and the depth of mesa etching. The frequency spectrum of the noise of sample 1# has an inflection point at about 10Hz frequency, 1/f noise play an obviously role in the detectors below the 10Hz frequency.
A planar-type InGaAs linear detector was designed and fabricated based on n-i-n+ type InP/In0.53Ga0.47As/InP epitaxial
materials. The major process of the detector contains planar diffusion, surface passivation, metal contact and annealing.
The I-V curves and the relative spectral response were measured at room temperature. The relative spectral response is in
the range of 0.9 μm to 1.68 μm. The R0A of the detector is about 2×106 Ω•cm2 and the dark current density is
5~10nA/cm2 at -10mV bias voltage. The linear detectors were wire-bonded with readout integrated circuits (ROIC) to
form focal plane array (FPA). The input stage of the ROIC is based on capacitive-feedback transimpedance amplifier
(CTIA) with a capacitor (Cint) to be 0.1pF. However, the FPA signals are oscillating especially when close to the
saturation. The ohmic contact on p-InP region plays an important role in the performance of detectors and FPAs. In this
case, the series resistance to p-InP layer of each pixel is up to 1×106Ω. The FPAs were simulated in case of InGaAs
detectors with different series resistances. According to the simulation results, the bandwidth of CTIA is lowering along
with Rs increasing, and the signals of the FPAs oscillate when the series resistances are beyond 4×104Ω. The reason for
the unstable oscillation of FPA is due to the series resistance of the detector which is too high enough. Then, the
annealing process of the detectors was improved and the series resistances were lower than 1×104Ω. The optimized
InGaAs linear detectors were wire-bonded with the same ROIC. The oscillation of the signals disappears and the FPA
shows good stability.
InxGa1-xAs ternary compound is suitable for detector applications in the shortwave infrared (1-3 μm) band. In this paper,
we reported on mesa type and planar type extended wavelength InGaAs detector arrays. The photo response
performances of these detector arrays were investigated. The blackbody responsivities (Rbb) of these detectors at different
temperatures were measured, and the results showed that the Rbb of planar type arrays was higher than that of the
conventionally passivated mesa type, but the mesa arrays fabricated by improved passivating technique has the highest
responsivity. The reason of the Rbb difference between the arrays was analyzed, and it is found that the difference mostly
comes from the minority carrier lifetime, which is related to the device structures and fabrication processes. With the
optimized fabrication processes the mesa type arrays can obtain higher blackbody responsivity even more than the planar
arrays.
According to excellent photoelectric properties of InGaAs epitaxial material, and important application of the spectral
bands at center wavelength of 1.38 μm and 1.60μm, the new-type monolithic dual-band InGaAs detector is studied in
this paper. The detector was designed and fabricated with mesa structure and Fabry-Perot cavity by thermal evaporation.
The current-voltage characteristics, response spectra of monolithic detector were measured. The bandwidths of 1.38 μm
and 1.60μm waveband detector are 46nm and 54 nm respectively. A 400×2 dual-waveband monolithic detector was
wire-bonded with two 400×1 readout circuits, to form 400×2 dual-waveband InGaAs focal plane arrays (FPAs). At room
temperature, the detectivity D*, non-uniformity, response bandwidth and the non-operative pixel ratio of 1.38 μm
waveband FPAs are 7.71×1011cmHz1/2/W, 6.20%, 46nm and 0.25%, respectively, and the ones of 1.60 μm waveband FPAs are 6.06×1011cmHz1/2/W, 3.20%, 54nm and 0.25%, respectively. The monolithic dual-waveband InGaAs focal plane arrays (FPAs) plays an important roles in developing compact, low-cost and high-precision photoelectric detection (imaging) system.
Effect of γ-ray irradiations on the performance of InGaAs infrared detectors was studied. Planar-type 24×1 linear detector arrays were fabricated on n-InP/n-In0.53Ga0.47As/n-InP epitaxial structure by sealed-ampoule diffusion method. The InGaAs detectors were irradiated by 100krad, 300krad γ-ray at 40rad/s. The dark currents increased about 170%, 300% respectively and both decreased about 23% at the 8th hours and about 40% at the 22th hour after irradiation. Then the dark currents almost remained stable until 10 days after irradiation. Current-Voltage characteristics of the planar-type detector were analyzed. The current mechanisms were dominated by diffusion current, shunts current and generation-recombination current before irradiation. The γ irradiation resulted to increase these three current components. Ten days after irradiation, three current components all recovered partially. Capacitance-Voltage characteristics were measured before and after irradiation. Effective doping densities (Neff) of InGaAs layer were deduced by fitting 1/C2-V curves. Neff of detectors which were irradiated by 100krad γ-ray increased after irradiation and remained the same until 10 days after irradiation. Neff of detectors which were irradiated by 300krad γ-ray unchanged after irradiation. The response spectrums both moved slightly towards shorter wavelength after irradiation and stayed the same until at least 10 days after irradiation.
Planar 64x64 In0.83Ga0.17As focal plane arrays (FPA) were fabricated in this paper. The properties of In0.83Ga0.17As photodetectors such as I-V, responsivity, detectivity were characterized. Theoretical analysis and measurement of the dark current behavior of the detectors at 200-300K were presented. The typical bad pixels caused by excessive dark current were analyzed, the result shows that they are mainly caused by more ohmic current and trap-assisted tunneling current component. Dark current density is 0.986μA/cm2 at an operating temperature of 200K and a bias voltage of -10 mV. The relative spectral response is in the range of 1.38 μm to 2.6 μm at 280K. The peak spectral response wavelength and quantum efficiency are 2.2 μm and 71.2% at 280K respectively. The achieved peak detectivity can reach 4.05x1011cmHz1/2W-1 by thermoelectric cooling at 200K.
InxGa1-xAs ternary compound is suitable for detector applications in the shortwave infrared (1-3 μm) band. The alloy In0.53Ga0.47As is lattice-matched to InP substrate, which leads to high quality epitaxial layers. Consistently the In0.53Ga0.47As detector shows low dark current density and high detectivity at room temperature with wavelength response between 0.9 and 1.7 μm. In this paper, planar-type 24×1 linear InGaAs detector arrays with guard-ring structure were designed and fabricated based on n-i-n+ type InP/In0.53Ga0.47As/InP epitaxial structure by sealed-ampoule diffusion method. At first the dark current density is about 30~60 nA/cm2 at -0.1 V at room temperature. After modifications to the detector design and processing, the dark current density reduces to 2~9 nA/cm2 at -0.1 V at 293 K. The ideality factors simulated from I-V curves come close to 1 and less than the factors of previous detectors, which indicates that the dark current is dominated by diffusion current, while the generation-recombination current exhibits in the previous detectors. At the temperature of 293 K, the R0A of the detector reaches more than 1×107 Ω·cm2, the relative spectral response is in
the range of 0.9 μm to 1.68 μm, the mean peak responsivity is 1.2 A/W and the mean peak detectivity is more than 3.0×1012 cm·Hz1/2/W.
Pyroelectric infrared linear arrays can work at ambient temperature without cryogenic system and have the merits of
comparatively homogenous spectral response in wide spectrum range, compact structure, long-time stability and low cost for many applications. xPb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)O3-(1-x-y)PbTiO3 (PIMNT) single crystal is a kind of novel pyroelectric material, which possesses superior pyroelectric performances and is appraised as a candidate for high performance pyroelectric infrared linear arrays. This paper describes the layout and essential properties of the pyroelectric infrared linear arrays based on PIMNT with 128 responsive elements. The transmittance measurement of PIMNT indicates that an absorption layer is needed when the PIMNT based linear arrays work at room temperature in 0.8—12.0 μm wave range due to the low absorption ratio especially in 0.8—10.0 μm wave band. The arrays employ a hybrid structure consisting of the PIMNT pyroelectric chip and CMOS read-out circuit. They are electrically bonded by ultrasonic bonding process. Also some details of the process technologies of the PIMNT pyroelectric chip are depicted in this paper.
A pyroelectric detector with special structure was developed for calibration of UV radiation. A new relaxor-based
ferroelectric single crystal with high pyroelectric coefficient was selected as the detector material. The detector is free of
substrate and a black coating film was deposited on the surface of the sensitive area. The reflectance of the coating film
is less than 1% in the spectral range 200nm to 400nm, and its sheet resistance is near 100 Ohm. Both the UV radiation
absorption and the electrically heating in the coating film can result in temperature change. Accordingly, the film can
work both as optical absorber and electric heater. By this means, the measurement of UV radiation power can be
converted to the measurement of electrical power. The direction of the heat flow is same in both cases, but the
mechanism of heat transport has tiny differences. A finite element model was set up by ANSYS software to simulate the
thermal diffusivity. The factors which may bring errors to the optical-electrical equivalence were measured and analyzed
in detail. The detectors were used to establish UV electrically calibrated system with uncertainty less than 4% in the
spectral range from 200nm to 400nm at room temperature.
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