Hole transport across the (Al,Ga)(As,Sb) barrier in InAs-(Al,Ga)(As,Sb) heterostructures

The current transport across the top (Al,Ga)(As,Sb) barrier in InAs-(Al,Ga)(As,Sb) heterostructures is investigated. It is shown that transport mechanism is a result of thermionic emission of holes over the valence band barrier. Temperature-dependent Hall measurements show that the deposition of a metal contact on the InAs cap layer shifts the pinning position of the Fermi level at the surface of the diodes, thus, an accurate zero-bias energy band diagram for the structures is obtained. Temperature dependence measurements of the thermionic currents reveal energy barrier heights that agree well with the expected energy barrier for thermionic hole transport in the valence band of the three (Al,Ga)(As,Sb) barriers. The voltage dependence of both the diode current and the extracted energy barrier height is shown to be consistent with the thermionic emission of holes over the valence band.