The role of atmospheric elements in the wide band-gap semiconductors

Abstract

The paper addresses the role of ambient elements (H, C, N and O) in the wide-bandgap semiconductor compounds. Their prevalence in the atmosphere imposes limitations not only on the purity of the materials under processing but, also, on the detection and measurement of the content of these species. Specifically, a review of electrical and optical properties, based on the available literature, is presented for: hydrogen in GaN, ZnO and SiC, carbon in GaN and ZnO, nitrogen in ZnO and SiC and oxygen in GaN and SiC. Further, the refinements of the SIMS (Secondary Ions Mass Spectrometry) analytical technique, aiming to improve the sensitivity and detection limit of atmospheric elements, are described in detail. These include the choice of primary beam type and current, type of secondary single or cluster ions, geometry and vacuum conditions. Finally, the evaluated so-called RSF parameters (Relative Sensitivity Factors) are given for each atom-semiconductor pair, converting raw data to the absolute value of concentration.