HgCdTe is the material of choice for the fabrication of high-performance cryogenic infrared detectors. The p-on-n double layer heterostructure design in HgCdTe device utilizes a high-composition layer to suppress surface leakage, thereby achieving low dark current and high R0A values. However, valence band barrier introduced by the high-composition layer may adversely affect the quantum efficiency of the detector. In this work, Silvaco TCAD simulations were employed to investigate the influence of material composition and doping concentration on valence band barrier in p-on-n double layer heterostructure. The simulation results revealed that a smaller composition difference and a larger composition gradient between the absorber layer and the high-composition layer lead to a smaller valence band barrier. Moreover, a higher doping concentration in the absorber layer results in a larger valence band barrier, while the doping concentration in the high-composition layer has a relatively minor impact on the valence band barrier. Based on these simulation findings, HgCdTe p-on-n double layer heterostructure materials were grown using the VLPE technique and the composition and doping profiles were characterized using SIMS measurements. The experimental results showed a composition difference of Δx=0.09 and a composition gradient of s=0.02μm-1 between the absorber and high-composition layers, with an In doping concentration of 1×1014cm-3 and an As doping concentration of 3×1017 cm-3 . Devices fabricated from these materials exhibited a noise-equivalent temperature difference of 20.1 mK, a dark current of 20.54 pA@ 9.67μm at 77K, which almost the same level with Rule 07 results.
KEYWORDS: Dark current, Sensors, Infrared detectors, Long wavelength infrared, Black bodies, Activation energy, Temperature metrology, Superlattices, Laser sintering, Gallium antimonide
Advances in bandgap engineering of various III-V compound semiconductors have led to innovative infrared detector architectures such as InAs/GaSb barrier-type structures. This barrier-type structure detectors are characterized by enhanced carrier transport optimization, a significant reduction in interface state density, and superior thermal stability, alongside a notable reduction in dark current and noise levels. These improvements not only substantially enhance the fundamental electrical characteristics of semiconductor devices but also expand their application flexibility and environmental adaptability through meticulous bandgap engineering. This article reports a study on optoelectronic properties based on a graded barrier InAs/GaSb T2SLs long-wave infrared detector for the first time, with detailed analysis from two aspects: electrical and optical properties. The surface leakage current is measured through variable area testing. The study correlates effective bandgap and activation energy across temperatures, providing insights into bulk dark current components. In addition, the temperature dependence of blackbody responsivity is also analyzed.
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.
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.
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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.