Dresden 2026 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 48: Heterostructures, Interfaces and Surfaces: Fabrication and Structure

HL 48.1: Vortrag

Donnerstag, 12. März 2026, 15:00–15:15, POT/0251

Cross-sectional scanning tunneling microscopy (XSTM) study of nearly lattice-matched III-V semiconductor heterostructures — •Hitesh Kumar¹, Rüdiger Schott², Zijin Lei², Werner Wegscheider², and Stefan Fölsch¹ — ¹Paul Drude Institute for Solid State Electronics, Berlin, Germany — ²Laboratory for Solid State Physics, ETH Zürich, Zürich, Switzerland

XSTM is a powerful technique for investigating the structural and electronic properties of III-V semiconductor heterostructures. These heterostructures are grown along the [001] direction by molecular beam epitaxy and accessible in cross-sectional view by cleaving the sample in ultrahigh vacuum to expose the (110) cleavage surface. We used this approach to study a GaSb-InAs-AlGaSb-InAs-InAsSb layered heterostructure grown on a Te-doped GaSb substrate. Voltage-dependent chemical contrast in STM imaging allows differentiation between anions and cations in the III-V semiconductors. Using this capability, we analyzed the degree of homogeneity in the ternary materials (Al-Ga mixing in the AlGaSb layer and As-Sb mixing in the InAsSb layer). With the help of scanning tunneling spectroscopy, we precisely determined the band gaps of the individual layers and locally probed the band lineup across the entire heterostructure. This allowed us to investigate the behavior of charge carriers governed by the band lineup. Specifically, we studied the spatial confinement and quantization of conduction band states in the InAs layer and their decay into the gap region of the adjacent layers.

Keywords: Scanning tunneling microscopy (STM); Cross-sectional scanning tunneling microscopy; Scanning tunneling spectroscopy (STS); Layered heterostructures; III-V semiconductors