Capacitance spectroscopy of InAs self-assembled quantum dots

Abstract

Capacitance spectroscopy is used to study electronic properties of self-assembled InAs quantum dots. The capacitance-voltage, C(V), measurements in combination with the magneto-capacitance, C(B), results make it possible to investigate the electrostatic profile of a series of single-barrier n-i-n GaAs/AlAs/GaAs heterostructures incorporating a layer of self-assembled InAs quantum dots in the AlAs barrier. We find that the negative charge associated with electron filling of the dots is closely compensated by a positive charge in the AlAs barrier, which we ascribe to ionised defects or impurities, possibly in association with the quantum dots. It is shown the compensation degree considerably depends on the growth conditions.