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.
The preparation of mesa-type InSb infrared focal plane detectors based on Be ion implantation was studied. The conventional furnace annealing of 350°C for 60 minutes was used to repair the lattice damage due to the implantation. The as-annealed InSb wafers were fabricated into InSb 128×128 array focal plane arrays with pixel size of 50 μm. The current-voltage and imaging characterization shows that the average peak detectivity reaches as high as 7.48×1010 cm·Hz1/2/W, with bad pixel ratio of < 0.5% and NETD of 28mK were achieved, implying the InSb detectors by Be implantation has considerable performance with diffusion ones.
In this work, Be ions were used for p-type doping by implantation because of its light mass and consequently lower damage introduction rate. Photodiode properties of implanted InSb with both conventional annealing and rapid thermal annealing were also presented. The p-on-n structure samples were fabricated by Be ions bombarding with the doses of 2×1014 cm-2 and 5×1014 cm-2 at room temperature. The implanting energy was chosen at 100KeV, 120KeV and 140KeV, respectively. Then SIMS measurements were taken to confirm the depth and doping concentration distribution. The rapid thermal annealing and conventional annealing were employed to make the comparison. The InSb photodiodes were fabricated using the process including mesa etching, passivation, and metallization. The current-voltage curves with both annealing methods were obtained at 77K, showing that the diodes with annealing condition of 350 .60 minutes has the highest zero-bias resistance. The diodes by conventional furnace annealing have better performance than that of rapid thermal annealing.
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