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HIGH RESOLUTION X-RAY DIFFRACTION AND TOPOGRAPHY ANALYSIS OF DEFECTS IN GaAs WAFERS Kaspar Roosalu, Jaan Aarik, Hugo Mändar Institute of Physics, University of Tartu, Estonia e-mail: [email protected] Silicon (Si), begin still the leader in the list of materials for electronic industry, is approaching to its physical limits when the properties like high voltage, blocking voltage, current capability, operation at high temperatures and frequencies are considered for high power and switching devices. Therefore gallium arsenide (GaAs) gained considerable attention in power and high-frequency applications over past decades already. Since defects (dislocations, inclusions etc.) have adverse effect on performance of semiconductor devices, it is important to characterize the quality of GaAs devices in various manufacturing stages, to optimize surface treatment and thin film growing methods in this respect. In this study we have employed X-ray diffraction topography (XRT) (figure 1) method to visualize the quality of GaAs wafer surface layers polished by mechanical and chemical procedures. R-ray reflection (XRR) and X-ray diffraction (XRD) rocking curve (RC) measurements are conducted to characterize the surface roughness, crystal mosaicity and presence of a damaged surface layer of GaAs substrates and epitaxial GaAs layers. We show that results from XRT analysis are in good agreement with RC measurements, and these methods in combination enable to select the wafers with lowest concentration of defects. Fig. 1 XRT patterns of GaAs epitaxial layer (left) and of corresponding GaAs substrate (right). TOETAB TÜ JA TTÜ DOKTORIKOOL “FUNKTSIONAALSED MATERJALID JA TEHNOLOOGIAD” (FMTDK) ESF PROJEKT 1.2.0401.09-0079