研究目的

To develop high-throughput depth-resolved electronic structure measurements using hard X-ray photoelectron spectroscopy (HAXPES) combined with X-ray total reflection (TR) and apply this method to probe the surface band bending of n-type polar GaN.

研究成果

The study successfully demonstrated depth-resolved electronic structure measurements by TR-HAXPES from ~2 to ~12 nm in depth for polar GaN. The surface band bending behaviors of the n-type Ga- and N-polar GaN surfaces were obtained, showing different behaviors related to the surface contaminations and crystal quality. The method offers fast data acquisition and less modification of the valence-band spectral shapes by the matrix element effects.

研究不足

The method requires a flat and smooth sample surface to find the X-ray total reflection critical angle. The surface condition of GaN strongly depends on its surface quality, making it difficult to determine the VBM near the surface and the band bending profile via surface-sensitive PES.