Microscopic characterization ofInAs/In0.28

Abstract

We have used cross-sectional scanning tunneling microscopy ͑XSTM͒ and transmission electron microscopy ͑TEM͒ to study InAs/In 0.28 Ga 0.72 Sb/InAs/AlSb strained-layer heterostructures designed for use in infrared lasers. The samples came from the same material previously characterized by photoluminescence ͑PL͒ and x-ray diffraction ͓M. J. Yang et al., J. Appl. Phys. 86, 1796 ͑1999͔͒. Several structures grown at different temperatures and with either III-As or III-Sb-like interfacial bonds have been characterized. Analysis of high-resolution TEM images finds the same degree of interfacial roughness ͑ϳ1 ML͒ for both III-As and III-Sb interfacial bonded heterostructures, despite significantly greater PL intensity in the latter. We also implement and compare two different methods for analyzing the interfacial roughness using XSTM; both show that the crucial InAs/InGaSb interface is rougher in the samples grown at high temperature. Even in samples grown at the optimal temperature ͑ϳ440°C͒, XSTM reveals intermixing at the AlSb-on-InAs interfaces, as well as unexpected differences in the interfacial bond types at the InAs-on-AlSb vs AlSb-on-InAs interfaces. Whereas all layers grown at or below the optimal growth temperature appear defect-free in TEM, threading dislocations are observed in samples grown at higher temperature.

Scanning tunneling microscopy on unpinnedGaN(11¯00)surfaces: Invisibility of valence-band states

“…This "atom-selective imaging" combined with the fact that ͑110͒ surfaces of GaAs and other III-V compound semiconductors provide perfect crosssectional cleavage surfaces, made the so-called crosssectional STM one of the most successful tools to investigate the atomic and electronic properties of defects, interfaces, epitaxial layers, and buried nanostructures with atomic resolution and thereby helped to unravel the processes acting during epitaxy of III-V semiconductor devices. [3][4][5] The principle of voltage-dependent tunneling suggests that it is always possible to image the filled and empty density of states of a sample, as assumed in general when interpreting scanning tunneling microscopy and spectroscopy measurements.…”

Dopant atom clustering and charge screening induced roughness of electronic interfaces in GaAsp-nmultilayers

“…This is best described in real space by the above-used Lorenzian function. We emphasize that the roughness amplitudes and correlation length obtained here for the doping interfaces are about one order of magnitude larger than those typically found for heterojunction interfaces consisting of different compounds, 11,13,14 because the latter probe primarily the metallurgical interface. Furthermore, the functional dependence found in Fig.…”

Room Temperature Carrier Kinetics in the W-type GaInAsSb/InAs/AlSb Quantum Well Structure Emitting in Mid-Infrared Spectral Range

“…One can point out at least two possible reasons leading to such an observation: (i) carrier escape from the QW to some population of e.g. optically inactive states spatially located at the InAs/Ga 0.80 In 0.20 As 0.15 Sb 0.85 heterointerface [10][11][12], or (ii) it can be attributed, as recently postulated [13], to the hole tunnelling out of its confining potential towards the GaAs 0.08 Sb 0.92 matrix. The first scenario cannot be totally excluded because the existence of non-radiative centres at the QW interfaces has already been confirmed in several experiments [10,12].…”