Temperature-dependent capacitance-voltage analysis of defects in Al2O3 gate dielectric stacks on GaN

Capacitance-voltage measurements of Pd/atomic layer deposited Al2O3/GaN metal oxide semiconductor capacitors performed over a temperature range of 77 K-500 K are reported. Border trap response is not detected in these measurements, consistent with the energy levels of bulk Al2O3 defects predicted in reported first principles calculations. The limitations of the conductance method for estimation of the interface state density of the wide band gap GaN semiconductor, even at a measurement temperature of 500 K, are discussed. As GaN-based devices are intended for high temperature applications, the role of the pyroelectric effect in the interpretation of higher-temperature capacitance-voltage data is described.