Incorporation of N in high N‐content GaAsN films investigated by Raman scattering

Abstract

AbstractHigh N‐content GaAs1–x Nx films (0 ≤ x ≤ 0.055) grown GaAs (001) substrates by MOVPE were investigated using micro‐Raman spectroscopy. The nitrogen local vibration mode (N‐LVM) which was clearly observed at around 468 ‐ 475 cm‐1 is used as a tool to examine the N incorporation. No change in the local environment of N is observed for the high N‐containing films with N contents up to x = 0.055. The use of 514.5 nm‐line Ar+ laser as the light source gives a linear dependence of the N contents determined by Raman spectroscopy (xRaman) on the N contents determined by the high resolution X‐ray diffraction (xXRD) for xXRD ≤ 0.055, providing a realizable calibration method to determine N content in the high N‐content GaAs1‐x Nx films. On the other hand, the use of longer wavelength (632.8 nm‐line He‐Ne laser) gives a best coincidence for only the lower N contents (x < 0.02). Since, the use of longer wavelength requires the thicker film owing to a thicker optical penetration depth. Thus, in our case, a deviation from the linear behavior for higher N contents, xXRD ≥ 0.02, is not due to the N‐related reasons, but this is the results of the additional Raman scattering intensity of GaAs‐LO from the substrate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)