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

Hole emission from self-organized Ge quantum dots with a diameter of simila r to 70 nm in a Si matrix is investigated by time-resolved capacitance spec troscopy [deep level transient spectroscopy (DLTS)]. A complex DLTS signal is observed and explained in terms of thermally activated emission from loc alized many-particle states. In particular, a gradually decreasing activati on energy is found with increasing hole population. A qualitative understan ding of the DLTS signal and the observed activation energies is achieved in terms of many-particle states determined by quantization and Coulomb charg ing. (C) 2000 American Institute of Physics. [S0003-6951(00)02952-1].