Abstract
High-quality InAs epilayers were grown onto GaAs (001) substrate by molecular beam epitaxy. The optimal growth conditions were examined over a wide range of substrate temperature, substrate offcut orientation, and As4/In flux ratio. The surface morphology, electrical and structural properties were investigated by Nomarski optical microscopy, Hall effect measurement, and X-ray diffraction, respectively. It is worth noting that InAs layers grown on GaAs (001) substrate with 2° offcut towards 〈110〉 have better crystalline quality and electrical properties than that grown on GaAs substrate without offcut. The results indicated that the layers grown at 400 °C, with a group V/III flux ratio of 8.5, yielded to the highest electrical quality, with a Hall mobility of 22,420 cm2/Vs at 80 K and 12,970 cm2/Vs at room temperature. It is found that the top part of 5 µm-thick InAs layer exhibits a high Hall mobility of 77,380 and 25,275 cm2/Vs, at 80 and 300 K, respectively.
Highlights
Epitaxial InAs structures has attracted interest in several device applications
It is worth noting that InAs layers grown on GaAs (001) substrate with 2° offcut towards h110i have better crystalline quality and electrical properties than that grown on GaAs substrate without offcut
InAs films have been used into devices such as high electron mobility transistor (HEMT) (Popovic et al 1996), Hall sensors
Summary
Epitaxial InAs structures has attracted interest in several device applications. Some of its potentially useful attributes enclose high electron mobility, narrow band gap, as well as the feasibility of ohmic contacts of many metals with InAs (Trampert et al 1995; Hooper et al 1993; Kalem 1989, 1990; Fang et al 1991). A huge number of these defects are located in the first few tenths of lm of InAs layer These dislocations notably pass away for a distance greater than a critical thickness (*0.2 lm) (Hooper et al 1993; Yamamoto et al 1997). Several types of buffer layer techniques have been developed in order to grow high quality InAs layer (Bolognesi et al 1994; Yasuda et al 2000; Ballet et al 2001). These buffer layers are time consuming and are not cost-effective. We report on the effect of growth temperature, group V/III flux ratio, and substrate misorientation on the electrical, structural and surface morphology properties of InAs layers grown directly on GaAs substrates by molecular beam epitaxy
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