HgCdTe films grown by Molecular Beam Epitaxy (MBE) are essential for creating high-performance Infrared Focal Plane Arrays (IRFPAs) like dual band detectors, High Operating Temperature (HOT) detectors, and Avalanche Photodiode (APD) detectors. CdZnTe is recognized as the optimal substrates for growing high crystal quality HgCdTe due to its lattice matching, which is adjusted by selecting the Zn mole fraction. If the Zn mole fraction in CdZnTe substrates falls outside the ideal range, it may lead to an increase in dislocation density in HgCdTe films, thereby adversely affecting the performance of the device. A proposed method has been introduced for designing a lattice-matching buffer layer between CdZnTe substrates and HgCdTe films. Growth of HgCdTe on CdZnTe substrates with an unsuitable Zn mole fraction was conducted with and without a lattice-matching buffer layer. Results showed that the dislocation density of the HgCdTe film obtained on CdZnTe substrates with an unsuitable Zn mole fraction usually exceeds 1×106 cm-2. However, as expected, the presence of a lattice-matching buffer layer significantly reduced the dislocation density of HgCdTe films. The dislocation density can be effectively controlled within 3×105 cm-2, with a mean value around 1×105 cm-2 . By doing so, the allowable range of Zn mole fraction in substrates for producing high-quality HgCdTe films can be widened, which holds significant engineering implications for the manufacturing of MBE HgCdTe.
Non-equilibrium photovoltaic HgCdTe detector with a P+ νN+ structure has been demonstrated to work at high temperature, in which carriers were swept out in a non-equilibrium condition, resulting in a significant decrease of carrier concentration. The P+ -type layer grown by Molecular Beam Epitaxy (MBE) is achieved by arsenic (As) doping, followed by high temperature annealing to activate As. However, due to the annealing temperature is higher than 400 °C, interdiffusion of cations (cadmium (Cd) ion and mercury (Hg) ion) can easily take place in such a high temperature, leading to a higher Cd component and shorter absorption region in the absorber layer, which can ultimately decrease the optical absorption and quantum efficiency of the device. Herein, we proposed a P+G4G3νG2G1N+ heterostructure, which can effectively trap the Cd ions diffusing from the P+ and N+ regions due to the component low-lying area between G4G3 and G2G1. In this work, we firstly investigated the performance using Silvaco, the simulation results indicated that this P+G4G3νG2G1N+ heterostructure can effectively achieve Auger suppression at 200K. High quality and uniform HgCdTe epilayers on CdZnTe substrate were fabricated. The effective thickness of the absorption layer after annealing reduced by more than 1.5 μm due to interdiffusion of the Cd ions in a conventional P+ νN+ structure. In sharp contrast, the effective thickness of the absorption layer after annealing reduced within 0.5 μm in the as-designed P+G4G3νG2G1N+, indicating an inspired way to fabricate high performance HOT non-equilibrium HgCdTe detector.
This paper reported the research of mid-wavelength infrared (MWIR) HgCdTe focal plane arrays (FPAs) detector with high operating temperature (HOT) at Kunming Institute of Physics. The fabrication of detector FPAs was based on high-quality in-situ indium-doped HgCdTe films grown by Liquid Phase Epitaxy (LPE). The p-on-n planar junction devices was fabricated by arsenic ion implantation technology. The HgCdTe chip arrays, and column-level ADC digital Silicon readout integrated circuit (ROIC) were interconnected to hybrid FPAs by flip-chip bonding using indium bumps. The compact and low-heat-leakage Dewar was designed and used to package the hybrid FPAs, and then one Integrated Dewar Cooler Assembly (IDCA) was prepared by coupling low-power miniaturized Stirling cryocooler to the Dewar. The dark current, noise equivalent temperature difference (NETD) and operability of the detector at different operating temperatures were tested. The test results indicated that the detector could work at the temperature above 150K.
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