Figure 4

Contour plots of DLTS signals as a function of temperature and applied sample voltage calculated for different limiting cases: when electrons are thermally activated from two deep energy levels, which are uniformly distributed in the space and the thermal electron emission is not influenced by the electric field effect (a), the thermal emission goes from two energy distributed levels localized in space (b), when the electron emission from the states is determined by electric field dependent tunneling and thermal processes can be neglected (c), properties of plots (b) and (c) using parameters for QD levels in Table 1 are combined in contour plot (d)