Highly strained InGaAs layers on GaAs grown by molecular beam epitaxy for high electron mobility transistors

Abstract

We have grown highly strained In x Ga 1− x As layers on GaAs, by molecular beam epitaxy, showing excellent electrical and optical quality for high electron mobility transistors (HEMTs). Over a very narrow range of substrate temperature from 400 to 420°C, the mobility of 6 nm thick In 0.35Ga 0.65As channel HEMTs at room temperature exceeds 6200 cm 2/V · s. Furthermore, the In composition can be increased up to 0.42 without generating misfit dislocations. The peak energy and full width at half maximum of a 77 K photoluminescence spectrum from an In 0.42Ga 0.58As/GaAs (well width = 6 nm) strained single quantum well are as small as 1.082 eV and 9.8 meV, respectively. The highly strained In x Ga 1− x As channel HEMTs (0.3 ≤ x ≤ 0.4) show superior transconductance over conventional In 0.25Ga 0.75As channel HEMTs.