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We report on unusual low temperature (175° C) heteroepitaxial growth of germanium thin films using a standard radio-frequency plasma process. Spectroscopic ellipsometry and transmission electron microscopy (TEM) reveal a perfect crystalline quality of epitaxial germanium layers on (100) c-Ge wafers. In addition direct germanium crystal growth is achieved on (100) c-Si, despite 4.2% lattice mismatch. Defects rising from Ge/Si interface are mostly located within the first tens of nanometers, and threading dislocation density (TDD) values as low as 106 cm− 2 are obtained. Misfit stress is released fast: residual strain of− 0.4% is calculated from Moiré pattern analysis. Moreover we demonstrate a striking feature of low temperature plasma epitaxy, namely the fact that crystalline quality improves with thickness without epitaxy breakdown, as shown by TEM and depth profiling of …
Publication date: 
1 Jul 2014

Romain Cariou, Rosa Ruggeri, Xi Tan, Giovanni Mannino, Joaquim Nassar, P Roca i Cabarrocas

Biblio References: 
Volume: 4 Issue: 7 Pages: 077103
AIP Advances