Investigation of a growth interruption under an As flux at AlSb/InAs interfaces with InSb bonds

Abstract

We report on an optimized growth interruption time under an As flux during the AlSb/InAs interface growth of unintentionally doped InAs quantum well structures. The migration-enhanced epitaxy method is used to create InSb interface bonds. After the deposition of the first In monolayer the surface is exposed to an As flux for different time periods, before the In shutter is opened again. Time-resolved reflection high-electron-energy diffraction (RHEED) and high-resolution transmission electron microscopy are used to characterize the interface. In combination with Hall measurements of single quantum well structures the interruption time is optimized. The interface quality depends on the RHEED intensity recovering during the interruption time under an As flux. If the interruption time is sufficient to reach the same RHEED intensity level as it is for the InAs growth, the electron mobility rises from 180,000 to 255,000 cm 2/V s at 77 K. Furthermore, we observed that a disordered surface during the interface growth can be incorporated into the layer, leading to amorphous regions directly above the interface. Moreover, the disordering depends on the crystal orientation and is larger in the [1 1 ̄ : 0] azimuth.