Study of the morphology of the InAs-on-AlSb interface

Abstract

Using an atomic force microscope, we studied various InAs-on-AlSb interface structures grown by molecular beam epitaxy. We found marked differences between the effects of the two interface bond configurations—InSb-like and AlAs-like—on the morphology of the subsequent InAs layer. In general, InSb-like interfaces lead to a much smoother InAs overgrown layer with clearly resolvable monolayer terraces. AlAs-like interfaces, on the other hand, lead to increasingly rougher InAs growth with longer As exposure. Previous studies have demonstrated a strong correlation between the interface configuration and the electron mobility in the InAs quantum well. The morphology and transport results we obtained indicate one reason for the influence of the interface configuration—a rough InAs layer.

Structure of InAs/AlSb/InAs resonant tunneling diode interfaces

“…[6][7][8][9][10] For example, two different types of interfacial bonds can be formed during the deposition of AlSb on InAs, either AlAs like or InSb like, depending on the III-V deposition sequence. It has been found both experimentally [11][12][13][14] and theoretically 15 that InSblike interfaces are generally more abrupt than those with AlAs-like bonds. For this reason, among others, AlSb-based tunneling devices are usually fabricated with InSb-like interfaces.…”

InAs-based quantum-cascade lasers

“…Existence of In-Sb or Al-As bonds at interfaces induces high strains and affects crystalline quality of the QCL structure, its average lattice parameter and electronic properties. During MBE growth the quality of InAs/AlSb interfaces can be controlled using special shutter sequences favoring formation of a desired type of the bonds 13 . The use of different growth conditions, including also variation of the V/III flux ratio, results in difference, sometimes significant, in performances of QCLs with nominally the same design.…”

Interrelationships in the electronic and structural characteristics of strained InAs quantum well structures

“…Previous reports [6][7][8][9][10][11][12][13] have detailed relationships between growth of the InAs-on-AlSb junction and properties of the subsequent InAs layer. For example, at the InAson-AlSb junction, InSb-like rather than AlAs-like bonds were found to be more favorable for the transport properties of the InAs layer [6].…”

“…As a result, techniques that include the deposition of indium before InAs growth are commonly employed to achieve bulk-like transport properties. Specifically, the ensuing arsenic flux (before InAs growth) stimulates two important processes: anion exchange [14,15] and surface roughening [8]. These processes ultimately lead to degraded electron transport in the InAs layer.…”