Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 38: Semiconductor substrates: clean surfaces

O 38.3: Talk

Tuesday, March 23, 2010, 15:30–15:45, H40

Cleaning of GaN(2110) surfaces by Ga deposition and desorption — •Simon Kuhr, Christian Schulz, Timo Aschenbrenner, Jan Ingo Flege, Thomas Schmidt, Detlef Hommel, and Jens Falta — Institute of Solid State Physics, University of Bremen, Germany

Cleanliness of substrates is a key issue in fabrication of optoelectronic devices since impurities sensitively affect atomic structure, electronic properties and reactivity of the surfaces being the basis of semiconductor devices. One promising cleaning technique concerning especially the removal of oxygen and carbon on polar GaN(0001) surfaces is the deposition of several monolayers of metallic gallium followed by thermal desorption (Schulz et al., pss (c), 6 (2009)). We present first results of the application of this technique to non-polar GaN(2110) surfaces heteroepitaxially grown on r-plane sapphire substrates by metalorganic vapor phase epitaxy. The cleaning process has been monitored by x-ray photoelectron spectroscopy measurements in order to perform a quantitative analysis of the reduction of contaminations and of the surface stoichiometry. In the course of investigation we have developed a cleaning cycle combining thermal degassing and Ga deposition/desorption steps leading to an effective reduction of the contaminants oxygen and carbon. In addition, the impact of the cleaning method on atomic structure and surface roughness has been investigated by low-energy electron diffraction as well as scanning tunnelling microscopy.