Type II indium arsenide/gallium antimonide superlattice photodiodes and infrared focal plane arrays

In this work, the Type II InAs/GaSb binary superlattices have been exploited particularly for photodiodes and their applications to focal plane arrays (FPAs). Empirical tight-binding method (ETBM) was developed to guide the superlattice design. Close matching between the theoretical predictions and experimental measurements was observed. Some of the critical growth parameters have been optimized and the material quality of the superlattices has been improved significantly. The surface roughness of finished detectors surface has reached 1.2-1.4 A over an area of 20 mumx20 mum, and around 1.0 A over an area of 5 mumx5 mum and below. The x-ray full width half maximum (FWHM) has been decreased to values below 20 arcsec, for both the center and the satellite peaks.; High performance photodiodes with cutoff wavelength around 5 mum, 7-8 mum, 18.8 mum, and 32 mum have been demonstrated. With the highly reproducible results, the world's first 256x256 Type II FPAs with cutoff wavelength around 8 mum were concept proved. Afterwards, uncooled FPAs with cutoff wavelength around 5 mum using a same format were first demonstrated in this material system. The application of the SUMO cells for indium and gallium, and the cracker cells for arsenic and antimony has greatly improved the growth uniformity and repeatability. My invention of the GaxIn1-x mixed interface engineering technique has solved the lattice mismatch problem for these superlattices in the mid to long wavelength infrared range. It also enables very short period superlattice in the longer wavelength range. For the focal plane arrays, I also developed the etching stop techniques using InAs0.9107Sb0.0893. Material growth of AlAs0.0832 Sb0.9168 was also studied for both etching stop technique and for hetero structure designs.