Type-II Indium Arsenide/Gallium Antimonide Material and Photodetectors for High Performance, High Temperature and Low Cost Infrared Detection and Imaging.

摘要

Type-II superlattices have unique properties that are very desirable for infrared detectors and focal plane arrays (FPAs). However, this technology still needs to be further developed to be able to substitute existing technologies, mainly HgCdTe. In mid-wavelength infrared (MWIR), high operating temperature is the ultimate goal. In long wavelength infrared (LWIR), the main challenges are finding a reliable passivation technique, further improvement of the electrical performance and the reduction of cost.;In this work, it is recognized that any further improvement of the device performance requires a deeper understanding of the fundamental properties of type-II superlattices. Empirical tight binding model was used to build a model that evaluates the change of band structure and band gap of type-II superlattice with temperature. Close agreement with experimental results was achieved by minimum number of fitting parameters. Also, steady state photoluminescence characterization technique and its evolution with temperature, excitation power and doping level was used along with the modeling of radiative and Shockley-Read-Hall recombination mechanisms to determine different recombination rates and identify the dominant mechanism. It was concluded that SRH lifetime is the dominant mechanisms for temperatures above 77 K and 80 ns lifetime gives the best agreement with experimental results.;To raise the operating temperature of MWIR detectors, insertion of a tunneling barrier along with reducing the concentration of minority carriers in the active region by increasing the doping level and optimizing the doping technique and proper use of a capping layer resulted in 35°C increase in maximum temperature for background limited performance to 190 K. FPAs were also fabricated using the new design.;Finally, an effort is made to bring down the cost of infrared detectors and imagers by growing them on GaAs substrate. The large lattice mismatch is gradually released by the growth of 4 microm thick GaSb buffer layer. LWIR detectors were realized with similar performance to detectors on GaSb substrate. By optimizing the temperature control technique, type-II materials with acceptable quality were grown on large wafers both for MWIR and LWIR and FPAs were fabricated out of it.