Real-time assessment of In surface segregation during the growth of AlSb/InAs(Sb) heterostructures

Abstract

Indium surface segregation is evidenced in real time by reflection high-energy electron diffraction (RHEED) during the molecular beam epitaxial growth of AlSb on InAs(Sb). The resulting interface width is determined from the RHEED specular beam intensity variation during the growth. It extends over several nanometers and increases with the growth temperature. Band structure simulations show that the indium segregation leads to a strong localization of the wave function associated to the first bound hole level at the AlSb on InAs(Sb) interface.

MBE growth and interface formation of compound semiconductor heterostructures for optoelectronics

“…7(a)]. We note here the absence of In-segregation in these SLs, in contrast to what has been observed when growth is performed at higher temperatures [22]. Although the width of the bright interfacial layers agrees well with the expected 2 ML InSb -1 ML intentionally inserted, 1ML arising from the In-Sb interfacial bonding configuration -the origin of the contrast in the HRTEM image is still under discussion.…”

Indium surface segregation in AlSb and GaSb

“…Note that the values of R given here for AlSb are lower than those reported in Ref [11]. because in this previous work R was calculated from o as R=exp À1/o .…”

“…If now the same type of experiment is performed on InAs, i.e. pre-depositing an increasing amount of InSb before starting the Al(Ga)Sb overgrowth, o is no more varying with y InSb [11]. The fact that o reaches its saturation value for the growth of Al(Ga)Sb on only one InSb or InAs monolayer means that the maximum amount of In atoms segregating when Al(Ga)Sb is grown on ''thick'' InAs(Sb) layer does not exceed one monolayer.…”

“…to the interface width. This specific RHEED behaviour can also be used to evaluate the amount of In atoms segregating into AlSb or GaSb [11]. The method consists in pre-depositing a small amount of InSb onto the Al(Ga)Sb surface before subsequent Al(Ga)Sb growth, the associated coverage (y InSb ) being typically varied from 0 to 2 ML.…”

“…It is now well established that In surface segregation prevents the formation of abrupt interfaces in these heterostructures. However, despite the drastic effect of this intrinsic phenomenon on the actual potential profiles at quantumwell interfaces, only scarce results are available for other In containing III-V heterostructures such as (Ga,In)As/InP [8], (Ga,In)P/GaAs [9] and In(-As,Sb)/(Al,Ga)Sb [10,11], although they are currently used for quantum device fabrication. The latter heterostructure is in this context prototypical: a lot of work has been devoted to the influence of the bonding (InSb-or (Al,Ga)As-like) at the interfaces on the electronic and optical properties [12][13][14], but little attention has been paid to In surface segregation effects at (Al,Ga)Sb on In(-As,Sb) interface.…”