ABSTRACT
This chapter identifies the effect of two common surface cleaning treatments on surface reconstruction, morphology and stoichiometry of both A- and B-type GaN, by employing a combination of in situ reflection high energy electron diffraction and scanning tunnelling microscopy, and ex situ XPS, and illustrates the contrasting behaviours of the two surface polarities. The preparation of clean GaN surfaces is necessary in order to study the fundamental properties of GaN surfaces, a subject of increasing scientific and industrial relevance. Preparation of clean surfaces is fundamental to device fabrication due to the significant effects of the surface preparation technique on metal-semiconductor contacts. Prior to cleaning, the surface exhibits flat terraces, separated by monolayer high steps, which are covered in a monolayer of small adsorbates. The nitride semiconductors have underpinned many recent developments in optoelectronics and have further potential in electronic devices such as high electron mobility transistors and heterojunction bipolar transistors.
