Energy Band Calculation And Characterization Of InAs/GaSb Type-? Superlattice Materials

High-performance,high-resolution and low-cost uncooled focal plane infrared detector is the development direction of the third-generation infrared detection technology.Numerous theoretical studies show that InAs/GaSb type? superlattice materials have large quantum efficiency and responsivity,and smaller tunneling current and Auger recombination rate.The cutoff wavelength of InAs/GaSb superlattice could be tuned from 3?m to 30?m by changing thickness of one period.InAs/GaSb superlattice has been thought to be the most preferred material for the third generation infrared detector.This study mainly investigates energy band calculation,material preparation and material characterization of InAs/GaSb superlattice,whose aim is simulation and calculation and material research.These results provide the theoretical basis for the realization of high performance devices.The energy band structure,cutoff wavelength,relative absorption and effective mass of InAs/GaSb superlattice are investigated using KP theory based on envelope function approximation.The effects of interfacial structure on the material properties are analyzed theoretically.It is found that the calculation results of InSb-like interface structure are closer to the experimental values,which can be used to more accurately predict the cutoff wavelength of materials.Based on the theoretical calculation,a 10 ML InAs/2ML InSb/10 ML GaSb superlattice structure with a cutoff wavelength of 6.2?m is designed.InAs/GaSb superlattice and InAs,GaSb thin films are grown by MBE.The surface composition and doping process of InAs and GaSb thin films are studied by XPS and Hall test.The results show that undoped films have no other impurities,and high doped p+GaSb,high doped n+InAs and low background carrier i-stucture are successfully fabricated for pin detectors.The structure quality of InAs/GaSb superlattice is characterized by AFM and HRXRD.The results show that the surface of sample is plat and the parameters such as the thickness of one period are close to the design values.The lattice strain and interface roughness are small.All of these prove great materials growth.The cutoff wavelength of the superlattice is obtained by photoluminescence spectra,which is close to the theoretical calculation.