Electrical Properties of Atomic Layer Deposited Aluminum Oxide on Gallium Nitride

摘要

We report on our investigation of the electrical properties ofmetal/Al2O3/GaN metal-insulator-semiconductor (MIS) capacitors. We determinedthe conduction band offset and interface charge density of the alumina/GaNinterface by analyzing capacitance-voltage characteristics of atomic layerdeposited Al2O3 films on GaN substrates. The conduction band offset at theAl2O3/GaN interface was calculated to be 2.13 eV, in agreement with theoreticalpredications. A non-zero field of 0.93 MV/cm in the oxide under flat-bandconditions in the GaN was inferred, which we attribute to a fixed net positivecharge density of magnitude 4.60x1012 cm-2 at the Al2O3/GaN interface. Weprovide hypotheses to explain the origin of this charge by analyzing the energyband line-up.