The effect of InAs quantum layer and quantum dots on the electrical characteristics of GaAs structures

InAs monolayer (QL) and self-aggregated quantum dots (QD) were grown by ato mic layer MBE at 460 degrees C on an n-type GaAs-buffer layer and were capp ed with a 2 X 10(6)/cm(3) n-type GaAs layer. QDs significantly reduce the c apacitance measured at 1 MHz compared to samples with QL, and the capacitan ce and conductance of QD samples exhibit strong frequency and temperature d ependence. The I-V measurements show that single QDs are laterally coupled depending on the temperature. The fast defect transients measured in the 10 ns to 1 ys range show that the charge and discharge of QDs is similar to e xtended defects indicating that the broad peak in capacitance DLTS spectra cannot be interpreted as isolated point defects. (C) 2000 Elsevier Science B.V. All rights reserved.