Growth And Characterization Of InAsSb Infrared Photoelectronic Film And Unit Device

InAsxSb1-x material has potential application as midwave and longwave infrared photodetctor because of its many merits such as stable structure, high mobility of carrier, low dielectric constant and so on. It is expected to have longer waveleghth response. But the lack of lattice-match substrate made it difficult to get high quality InAsSb films. So the growth, structure and characterization of InAsSb film were investaged firstly, then high quality InAsSb/InSb superlattices unit device are made, and the IV and photoelectric properties of SLSs are studied.The InSb buffer grown by two steps was studied. The influences of processing parameters of InSb film such as substrate temperature, V/III ratio, low-temperature buffer thickness and InSb film thickness on quality of InSb film were studied and the optimized growth parameters were obtained. When the 40nm-thick low-temperature InSb nucleation layer was grown at 345℃, V/III ratio was 1.5 and growth speed was 0.2μm/h, then the InSb layer was grown at 390℃-415℃, V/III ratio was 3.6 and growth speed was 1.2μm/h, high quality InSb films were obtained. When the nucleation layer is 43nm thick, the growth mode of InSb films is 2D nucleation mode. And when the nucleation layers are 0, 65nm and 87nm respectively, the growth mode of InSb fims is step flow mode.The effects of processing parameters and buffers on Sb composition and qualities of InAsSb films were investigated. When the InAsSb films were grown under As₄ atmosphere, substrate temperature and As₄/Sb₄ ratio have weak influences on the Sb compositions of InAsSb films. If substrate temperature is higher than 420℃,the quality of InAsSb films are deteriorated. However, when the InAsSb films are grown under As₂ atmosphere, substrate temperature and As₂/Sb₄ ratio have strong influence on the Sb compositions of InAsSb films. Even if the substrate temperature is 450℃,high quality InAsSb films are still obtained.The electric properties of n-type and undoped InAsSb films under different temperature are investigated through Hall measurement, following the study of the influence of magnetic field on Hall effects. The experimental results of Hall coefficients and magnetic resistacnces in different magnetic field and Hall mobilities in different temperature agree with theory well. The results show that the InAsSb film grown under optimized growth parameters has excellent electricity properties: Hall mobility of InAsSb film doped at 3.5×10¹⁸cm^-3 is 19000cm²/V·s at 300K and 27500 cm²/V·s at 77K; and that of undoped InAsSb film is 34000cm²/V·s at 300K and 22500 cm²/V·s at 77K.The optical properties of InAs1-xSbx films are studied using Fourier transform infrared system. The results show that the relationship between Sb composition and band-gap fits the classical equation, except mid Sb compostion. The band-gap of InAs0.47Sb0.53 is much larger than classical value.InAsSb/InSb superlattice photodiode for longer wavelength infrared detection was designed and prepared. The results of high-resolution x-ray diffractometry and high-resolution electron microscopy show that the InAsSb/InSb superlattice has very excellent structure and crystallizaion quality, so it has excellent photoelectric properties. The photediode has responsivity at 2.7-3.5μm,4-12μm, and 15-25μm. Response at 2.7-3.5μm and 15-25μm disapears as temperature increases. The noise increases with temperature increasing, and the responsivity at 10-12μm is submerged eventually as noise increasing. While the responsivity at 4-10μm exists at 260K.