In-situ, real-time spectral reflectance monitoring of GaN growth

Abstract

An in-situ, real-time spectral reflectance (SR) technique was used to monitor the GaN growth during metalorganic chemical-vapor deposition. A series of SR spectra from 190 ∼ 861 nm were obtained using p-polarized light with an incident angle of 75°. The SR spectra could be nicely fitted with the known refractive indices of GaN and sapphire and with the GaN thickness as a fitting variable. The fitted thickness was in good agreement with the thickness measured by scanning electron microscopy. Furthermore, the peak positions of SR spectra increased linearly to longer wavelength with thickness. This strongly implies that thickness information can be obtained in real-time by measuring the peak shift of SR spectra, not by fitting the whole spectrum at that moment.