Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 6: Semiconductor substrates: Adsorption

O 6.2: Talk

Monday, March 14, 2011, 11:30–11:45, WIL B122

In situ surface analysis of Ge(100) for III-V heteroepitaxy — •Sebastian Brückner¹, Enrique Barrigón², Oliver Supplie¹, Johannes Luczak¹, Peter Kleinschmidt¹, Henning Döscher¹, Ignacio Rey-Stolle², Carlos Algora², and Thomas Hannappel¹ — ¹Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany — ²Instituto de Energía Solar, Universidad Politécnica de Madrid, ETSI de Telecomunicación, Avda. Complutense s/n, 28040 Madrid, Spain

Ge(100) is the established substrate for current world record III-V triple junction solar cells. However, uncertainties still remain regarding the atomic surface structure of the Ge(100) substrates prior to the MOVPE III-V heteroepitaxy. Here, we have applied in situ reflectance anisotropy spectroscopy (RAS) to study the influence of different group V precursors and reactor background contaminations on Ge(100) surfaces, that affect the subsequent III-V layer growth. A contamination free MOVPE to UHV transfer system allowed us to analyse different Ge(100) surfaces with various UHV based surface sensitive techniques such as x-ray photo electron spectroscopy (XPS), low energy electron diffraction (LEED), and scanning tunneling microscopy (STM). In this way, we were able to correlate the results of these surface analysis with the characteristic in situ RA spectra of the different clean, As and P terminated Ge surfaces. For instance, XPS measurements confirmed oxide removal and the corresponding termination. On the other hand, LEED measurements showed the influence of group V precursors and background As pressure on the surface reconstruction.