Electronic and vibrational states in InN and InxGa1−x N solid solutions
- 1 August 2004
- journal article
- Published by Pleiades Publishing Ltd in Semiconductors
- Vol. 38 (8), 861-898
- https://doi.org/10.1134/1.1787109
Abstract
The review presents the results of optical studies of the fundamental physical characteristics of InN, the material which remains the least studied among nitrides of Group-III elements. The results of early optical studies of InN are analyzed and compared with recent data. New experimental facts reported in the review refer to hexagonal single-crystal epitaxial InN layers with an electron concentration of (1−2)×1018 to 6×1020 cm−3, which are grown by molecular beam epitaxy (MBE) and metal-organic vapor-phase epitaxy (MOVPE) on Al2O3 substrates. The aim of this review is to make a joint analysis of optical spectra (absorption, photoluminescence (PL), PL excitation, and photomodulated reflection) near the fundamental band gap. Furthermore, basic structural and electrical characteristics that have been obtained by a whole range of techniques are given for epitaxial layers of hexagonal InN. The principal result of recent studies is that the hexagonal InN crystal is a narrow-gap semiconductor with a band gap of 0.65–0.7 eV. Previously, the band gap of this material was considered to be 1.89 eV. It is shown that the Burstein-Moss effect accounts for the strong difference between the band gap and the optical absorption threshold in InN samples with a high concentration of electrons. The small value of the band gap of hexagonal InN is confirmed by optical studies of InxGa1−x N solid solutions at high concentrations of In. Theoretical calculations of the band structure of hexagonal InN crystals are briefly reviewed.Keywords
This publication has 124 references indexed in Scilit:
- Correlation between strain, optical and electrical properties of InN grown by MBEphysica status solidi (c), 2003
- Localization of Excitons at Small In Clusters in Diluted InGaN Solid Solutionsphysica status solidi (c), 2002
- InN thin films grown by metalorganic molecular beam epitaxy on sapphire substratesJournal of Crystal Growth, 2001
- Experimental and theoretical studies of phonons in hexagonal InNApplied Physics Letters, 1999
- Growth of cubic InN on InAs(001) by plasma-assisted molecular beam epitaxyJournal of Crystal Growth, 1999
- Raman spectra of indium nitride thin films grown by microwave-excited metalorganic vapor phase epitaxy on (0001) sapphire substratesApplied Physics Letters, 1996
- Thermal stability of indium nitride single crystal filmsJournal of Applied Physics, 1993
- Evaluation of a new plasma source for molecular beam epitaxial growth of InN and GaN filmsJournal of Crystal Growth, 1991
- Percolation processes in three dimensionsJournal of Physics A: General Physics, 1976
- Thermal stability of indium nitride at elevated temperatures and nitrogen pressuresMaterials Research Bulletin, 1970