Scanning tunnelling microscopy imaging and modification of hydrogen-passivated Ge(100) surfaces

Abstract

Scanning tunnelling microscopy (STM) study and modification of hydrogen (H)-passivated Ge(100) surfaces have been investigated. Thermal oxidation procedures were used to minimise surface roughness. Ge samples were passivated in HF solution after thermal oxidation. STM and atomic force microscope (AFM) imaging showed that, using HF etching after thermal oxidation, we can obtain a natural H-passivated topographically and chemically flat Ge(100) surface. The root-mean-square (rms) roughness ofa H-passivated Ge(100) surface measured both by STM and AFM is less than 2 Å. Electric properties of H-passivated Ge(100) surfaces were studied by scanning tunnelling spectroscopy (STS) in nitrogen ambient. STS showed that the H-passivated Ge surfaces were not pinned. Modification on H-passivated Ge(100) surfaces was carried out using STM by applying an electric voltage between the sample and tip in air. Modified features were characterised by STM and AFM imaging. On the H-passivated Ge(100) surfaces, stable, low-voltage, nanometer-scale modified features can be produced.

Atomic-scale patterning of hydrogen terminated Ge(001) by scanning tunneling microscopy

“…Modification of H-terminated Ge surfaces with scanning probes has been limited so far to micron-scale features on Ge(001), patterned in an ambient nitrogen atmosphere with no atomic resolution STM image [22], or isolated hydrogen atoms desorbed from Ge(111) [23]. We exploit the imaging capability of the UHV-STM to optimize the initial Ge(001) surface preparation and hydrogen termination procedure and obtain an atomically flat low defect monohydride saturated Ge(001) surface.…”