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3 May 2010 Epitaxy ready 4" GaSb substrates: requirements for MBE grown type-II superlattice infrared detectors
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In this work newly developed 4" GaSb substrates are investigated for their suitability in the epitaxial growth of type II InAs/GaInSb superlattice detectors. The Czochralski technique was used to grow 4" GaSb crystals with etch pit densities in the range of 1.5-2.5E3 cm-2. Bulk crystal structure was investigated by X-ray topography and revealed large central areas of zero or low dislocation density. Epitaxy-ready substrate surfaces were characterized by low levels of surface roughness and uniform oxide coverage. The material quality of superlattice detector structures grown on 2" and 4" GaSb substrates has been compared. Surface morphology evaluations of a 4" GaSb epiwafer reveal very low haze surface and defect density level that is similar to a 2" epiwafer. An rms surface roughness of 4.4 A was measured by AFM which is only 1-2 A larger than seen on 2" diameter SLS epiwafers. High resolution X-Ray measurements of the epitaxial layer structure indicate high structural quality and reproducible SL periodicity. Good layer thickness uniformity with a center-to-edge variation just over 2% has been achieved.
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Mark J. Furlong, Rebecca Martinez, Sasson Amirhaghi, Dmitri Loubychev, Joel M. Fastenau, Xing Gu, and Amy W. K. Liu "Epitaxy ready 4" GaSb substrates: requirements for MBE grown type-II superlattice infrared detectors", Proc. SPIE 7660, Infrared Technology and Applications XXXVI, 76601K (3 May 2010);

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