Many-particle effects in Ge quantum dots investigated by time-resolved capacitance spectroscopy

Abstract

Hole emission from self-organized Ge quantum dots with a diameter of ∼70 nm in a Si matrix is investigated by time-resolved capacitance spectroscopy [deep level transient spectroscopy (DLTS)]. A complex DLTS signal is observed and explained in terms of thermally activated emission from localized many-particle states. In particular, a gradually decreasing activation energy is found with increasing hole population. A qualitative understanding of the DLTS signal and the observed activation energies is achieved in terms of many-particle states determined by quantization and Coulomb charging.