The surface electronic states of p-type GaN and its effect on the light-emitting diodes (LEDs) containing such p-GaN layers are studied. The surface band bending of p-GaN layers prepared from different growth conditions are determined by ultraviolet photoemission spectroscopy and X-ray photoemission spectroscopy. By either way, it is found that the surface band bending depends on the growth conditions and is reduced by increasing Mg concentration, growth temperature, and N2-rich ambient. A further reduction in band bending is found with a postannealing at 750°C in N2, resulting in a similar reduction of the operation forward voltage of the LED containing such a p-GaN layer. The mechanism involved is discussed.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry