Tunnelling and thermoactivation in self-assembled quantum dots

Recent photocurrent experiments in arrays of self-assembled quantum dots (QD) in p-i-n and n-i-p diodes demonstrate strong sensitivity to electric field applied along the growth direction. We show how the photocurrent measurements can be used to obtain the binding energy of electrons and holes in a QD. To calculate the photocurrent we employ the kinetic equation that takes into account tunneling, thermal activation and recombination of carriers. We study the limiting cases of strong and high applied fields and propose an interpolation expression for the photocurrent. The result is in excellent agreement with experimental data.