CURRENT-VOLTAGE CHARACTERISTICS OF STRAINED PIEZOELECTRIC STRUCTURES

Experimental and theoretical studies are presented of the current-voltage characteristics of symmetrically doped n-type GaN-AlN-GaN semiconductor- insulator-semiconductor (SIS) structures. The asymmetry caused by the strain-induced electric field leads to the depletion layer barrier in addition to the barrier presented by a thin insulating layer of AlN. It is shown that the tunnel current depends on the degree of the elastic strain relaxation which, in turn, is related to the AlN film thickness. This dependence provides quantitative information about the film relaxation. This characterization technique is compared with the capacitance-voltage characterization of the SIS structures. The data indicate that the low bound of the conduction-band offset for the AlN/GaN heterointerface is close to 1 eV. © 1995 American Institute of Physics.