Experimental Study of Hydrogen-Nitrogen-Hydrogen Centers in Dilute III-Nitrogen-V Alloys by Low-Temperature Vibrational Spectroscopy and Uniaxial-Stress Methods.

摘要

In this dissertation, hydrogen-containing defects in two kinds of semiconducting materials are studied: the dilute IIV-N-V alloy GaAsN and the metal oxides.;In both material systems, H has a significant effect on properties. In the dilute IIIV-N-V alloy GaAsN, there has been tremendous interest due to a large bandgap reduction caused by the introduction of N. Hydrogenation of these materials increases the band gap energy to near the value of the N-free host. A canted H-N-H defect was proposed to be the cause of the band gap recovery. Previous research using vibrational spectroscopy showed that the N-H complex in the IIIV-N-V alloy GaAsN contains two weakly-coupled N-H stretching modes which is consistent with the canted H-N-H model. We have used vibrational spectroscopy with uniaxial stress to investigate the symmetry of the H-N-H complex and to determine experimentally its microscopic properties. Our results show that the H-N-H complex has C1h symmetry and have determined its cant angle. Further studies by theory and experiment have suggested the formation of defect complexes that contain more than two H atoms per N atom. New IR results for GaAsN samples into which D was introduced at reduced temperature provide experimental clues about the structure of NH n defect complexes with n>2. We find that there is not a unique defect when additional H is added at lower temperature and that several defects coexist.;A variety of hydrogen-related defects exists in oxides and much attention has been focused on the identification, formation and microstructure of these defects. Since the hydrogen-stretching mode can be excited cleanly and is usually well separated in energy from the phonon bath, crystalline oxides are ideal systems to investigate the energy dynamics of hydroxyl groups. Our studies have provided information about the lifetimes of the hydrogen-stretching modes of the H-related defects in oxides which is important for dynamic studies of proton tunneling.