Interfacial band parameters of ultrathin ALD-ZrO2 on Ga-polar GaN through XPS measurements

Recent demonstrations of grafted p-n junctions combining n-type GaN with p-type semiconductors have shown great potential in achieving lattice-mismatch epitaxy-like heterostructures. Ultrathin dielectrics deposited by atomic layer deposition (ALD) serve both as a double-sided surface passivation layer and a quantum tunneling layer. On the other hand, with excellent thermal, mechanical, and electrical properties, ZrO2 serves as a high-k gate dielectric material in multiple applications, which is also of potential interest to applications in grafted GaN-based heterostructures. In this sense, understanding the interfacial band parameters of ultrathin ALD-ZrO2 is of great importance. In this work, the band-bending of Ga-polar GaN with ultrathin ALD-ZrO2 was studied by x-ray photoelectron spectroscopy (XPS). This study demonstrated that ZrO2 can effectively suppress upward band-bending from 0.88 to 0.48 eV at five deposition cycles. The bandgap values of ALD-ZrO2 at different thicknesses were also carefully studied.