Characterization of Shallow- and Deep-Level Defects in Undoped Ge1−xSnx Epitaxial Layers by Electrical Measurements

Abstract

Shallow- and deep-level defects in undoped Ge1−xSnx epitaxial layers on Ge and Si grown by molecular beam epitaxy and metal–organic chemical vapor deposition were investigated by Hall effect, capacitance–voltage, and deep-level transient spectroscopy (DLTS) measurements. We discuss the effects of postdeposition annealing and introducing hydrogen during crystal growth on shallow-level defects in undoped Ge1−xSnx epitaxial layers. Using DLTS measurements, we found shallow- (<EV+0.05 eV) and deep-level (EC−0.23 to EC−0.33 eV) defects in undoped Ge1−xSnx grown on Ge. We conclude that one of the candidates for the shallow-level defect is related to dislocation in the epitaxial layers.