Charging dynamics and electronic structure of excited state in Ge self-assembled quantum dots

Admittance measurements as a function of gate voltage, frequency, and tempe rature were made in a self-assembled Ge dot array embedded in Si (001) barr iers. The charging dynamics of the first excited state of the dots was stud ied. Four well-resolved maxima were observed in the conductance-voltage cha racteristics of the sample which contains about 10(9) dots. An equivalent c ircuit, which includes the response from the dots, successfully predicts th e observed behaviour of the capacitance and conductance dependence on the f requency. The hole emission time constants, the activation energies and the capture cross sections associated with the quantum levels in the dots were determined.