Effects of Rapid Thermal Processing on SiO2/GaAs Interfaces

Effects of rapid thermal processing (RTP) on SiO2/GaAs interfaces have been investigated with Auger electron spectroscopy and X-ray photoelectron spectroscopy. SiO2 films of 100, 175, 200 and 1250 nm thickness have been deposited on liquid encapsulated Czochralski-grown (100) n-type GaAs wafers by the RF sputtering method. RTP has been performed at 800°C for 6 s. For comparison, conventional furnace processing (CFP) has also been performed at 800°C for 20 min for 200-nm-thick SiO2/GaAs. The Ga is observed on the outer SiO2 surface for RTP samples as well as CFP samples. This indicates that the outdiffusion of Ga occurs after only 6 s at 800°C even through 1250-nm-thick SiO2 films. The depth profile of Ga reveals the pile-up of Ga on the outer SiO2 surface for both RTP and CFP samples. The amount of Ga on the outer surface gradually increases in the thickness range 1250 to 175 nm. The As is also observed on the outer surface. The amount of Ga and As on the outer surface rapidly increases at 100 nm thickness. Electron traps in RTP samples have been studied with deep-level transient spectroscopy. Different electron traps are produced in GaAs by RTP between 100-nm- and 200-nm-thick SiO2/GaAs. It is thought that the production of different traps by RTP is related to the amount of Ga and As loss through SiO2 films from GaAs.