Investigation On Growth And Characterization Of InGaAs For Uncooled Infrared Detector And Focus Plane Array

Uncooled infrared detectors and arrays are one of the most important developments in the infrared detection. InxGai.xAs ternary alloy has been of great interest for short wavelength infrared detector application. The x=0.53 InxGai.xAs alloy is lattice-matched to InP substrate and covers the wavelength range from 0.9 to 1.7 um. At present, InGaAs is becoming the best choice for room temperature operation in the 1-3 um spectrum. The imaging and spectroscopy are the major applications of InGaAs focal plane array.In this thesis. InxGai.xAs/InP heterostructure was grown by low pressure metalorganic chemical vapor deposition (LPMOCVD) technique. The LPMOCVD system was made by our group. The growth and characterization of Ino.53Gao.47As ternary alloy were studied in detail. The experiments show:Growth temperature is one of the key growth parameter by which the surface morphology, alloy composition, crystalline quality, mobility and carrier concentration are influenced. The high quality Ino.53Gao.47As can be obtained in the range of 630C -650 C.The surface morphology is greatly influenced by V/III ratio. Increasing V/II1 ratio is of great advantage to obtain high quality of Ino.53Gao.47As. The mobility of InGaAs epilayer increases when increasing the V/III ratio. The intrinsic carrier concentration reduces when decreasing the V / III ratio. The high quality of In0.53Gao.47As can be obtained at the range of 10-30 seconds of exchange time between AsHs and PHs. When the thickness of the buffer layer between the InPsubstrate and InGaAs epilayer is 0.2 um the mobility becomes the maximum and the carrier concentration is the lowest.Effect of growth parameters on photoluminescence of room temperature and low temperature (10K) was studied. Two PL peaks are found in the InGaAs PL spectrum at 10K when growth temperature is at 550C. Only one PL peak is found when growth temperature is in the range between 630C and 650C, the intensity of PL at 650C is more than one at 630C. The FWHM of PL at 650C is the narrowest .The variation of PL with excited intensity and temperatures were discussed respectively. The peak energy of PL at varied temperatures is calculated.Effect of growth parameters on Raman scattering spectra of InGaAs was also studied. Micro-Raman scattering experiments have identified the extra mode as a folded-longitudinal-acoustic (FLA) phonon mode; the intensity of this peak can be used as a measure of ordering of InGaAs. Temperature-varied Raman scattering spectra were obtained from 80K to 300K. The difference in the frequencies of their GaAs-like longitudinal optical phonons was used to calculate stress for the In0.53Ga0.47As/InP. leading to a direct formula for the evaluation of the layer stress.High quality wafer with InGaAs detector array have been successfully grown by LPMOCVD and were characterized.