Lateral conductivity in GaAs/InAs quantum dot structures

Lateral conductivity effects have been investigated in self-organised InAs quantum dot (QD) structures grown in a GaAs matrix with different cap layers. Current-voltage (I-V), capacitance-voltage (CV), DLTS, capacitance and conductance frequency dependence, fast defect transient (FDT), and electron beam induced conductivity (EBIC) measurements were applied. The conductivity in the QD plane decays within a distance of 10 microns. The capacitance transients are dominated by the local QD-plane transversal conductivity and by the free carrier transport in the cap layer. The nonequilibrium free carrier created by electron beam excitation develop a potential barrier at macroscopic distances from the electrical contacts.