Core–shell heterostructures have attracted extensive attention in the photoelectric field because of their improved optoelectrical properties. In this study, we report a novel self-powered ultraviolet (UV) photodetector based on In2O3/InN nanorods (NRs) core-shell heterostructure developed on the corrugated V-grooved Si (100) substrate. Under 365 nm UV light the hybrid heterostructure demonstrates remarkable photo-to-dark current ratio, high detectivity (64.85 A/W), responsivity (8.5 × 1012 Jones) excellent external quantum efficiency (9.15 × 103 %) and fast rising/falling times in a self-driven mode (0 V). This remarkable photoelectric detection capability is attributed to the strong absorption and abundant trapping of UV light by the multiple scattering of V-grooved texture and formation type-II heterojunction between the In2O3 and InN NRs core-shell structure resulting self-power mode, which enable notable charge separation and fast electron transfer. These accomplishments set the stage for future optoelectronic applications of III-nitride based core-shell heterostructure UV photodetectors that are self-powered.
In this work, we improved charge carrier separation efficiency through a g-C3N4/GaN NRs heterostructure device. We characterized the properties of the g-C3N4/GaN NRs device with detecting the UV light and sensing NO2 gas at room temperature. The device showed high responsivity and detectivity under zero bias conditions due to the built-in field at the interface of the heterostructure. The performance of the heterostructure was stimulated under UV light illuminations with 2.3 times higher response compared to the darkness. In addition, the device response to NO2, NH3, H2, H2S and CO ambient gases at RT were measured, the device exhibited high response to NO2 gas. The low activation energy promoted to capture NO2 gas molecules.
In this study, we report the results of confirming the possibility of optical fiber temperature sensors by fabricating cholesteric liquid crystal (CLC) cells combined with optical fibers. The CLC cell was fabricated with a Fabry-Perot etalon using the cross-sections of two optical fiber ferrules as substrates. A 1.2 um wide bandwidth wavelength swept laser was used to measure the spectrum change of the CLC cell according to the applied temperature. The reflection spectra were measured by changing the temperature of the CLC cell at intervals of 2o from 23o to 45o, and it was confirmed that the reflection band shifted discontinuously to a shorter wavelength as the temperature increased.
KEYWORDS: Semiconductors, Semiconductor materials, Thin films, Solid state lighting, Light emitting diodes, Solid state electronics, Field emission displays, Thin film devices, Magnetic semiconductors, Manganese
The novel green luminescent material of the semiconductive nanoporous ZnMnO thin film was fabricated by grain boundary engineering and thermal stress engineering via the thermal nucleation of the sputter-grown ZnMnO layers. Nanoporous ZnMnO exhibited the strong green luminescence characteristics, attributing to the photon confinement at the localized green-emission band formed near the edge area of ZnMnO nanopores. Using semiconductive nanoporous ZnMnO, two different types of high-performance solid-state lighting devices (i.e., field emission device and light-emitting diode) were demonstrated as tangible applications of semiconductive nanoporous ZnMnO.
In this work, we have investigated the variation of internal electric field of 4-period In0.16Ga0.84N/pseudo-AlInGaN multiquantum wells (MQWs) embedded in p-i-n structure by surface acoustic waves (SAWs). The pseudo-AlInGaN barriers consist of two In0.16Ga0.84N(11 Å) sandwiched by three Al0.064Ga0.936N (15 Å). The equivalent indium and aluminum compositions in pseudo-AlInGaN barrier are 0.043 and 0.052, respectively, which can be calculated by volume ratio. For reference purpose, In0.16Ga0.84N/GaN MQWs was also used. To generate surface acoustic wave, interdigital patterns with 1 μm finger width were fabricated by e-beam lithography. The piezoelectric fields for GaN barrier and pseudo- Al0.043In0.052Ga0.905N barrier samples are found to be 1.5 MV/cm, 0.33 MV/cm from bias-PL. From μ-PL measurement for pseudo-Al0.043In0.052Ga0.905N barrier sample, we observed lowest luminescence intensity at 100 MHz and 13 dBm in radio frequency (RF) generator, which means that electron-hole recombination can be suppressed by SAWs. The Photocurrent measurement for pseudo-Al0.043In0.052Ga0.905N barrier sample was observed increasing around 2 orders of magnitude at 100 MHz when compare to GaN barrier sample. Based on our results, the reduced piezoelectric field added to SAWs can be provided one of the solutions for enhancing photocurrent in III-nitride photovoltaic devices by extract carriers from quantum wells easily and enhancing traveling length of carriers.
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