Raman spectroscopy of GaN, AlGaN and AlN for process and growth monitoring/control

Abstract The use of micro‐Raman spectroscopy to monitor non‐invasively GaN, AlGaN and AlN material parameters for process and growth monitoring/control is demonstrated. Concepts to determine the crystalline quality, the stress, the free carrier concentration, the aluminium composition and the temperature from the Raman modes are reviewed. Raman monitoring of processing and growth is illustrated on selected examples: the high‐temperature processing of ion‐implanted and non‐implanted GaN layers, the Raman monitoring of AlGaN/GaN heterostructure field‐effect transistors and the in situ Raman monitoring of GaN growth at elevated temperatures. Ultraviolet Raman spectroscopy has been employed to characterize material properties of GaN surface layers and GaN/AlGaN interfaces. Raman mapping is illustrated on bulk AlN crystals to investigate stress fields related to growth striations and defects. Copyright © 2001 John Wiley & Sons, Ltd.