Optical properties of GaN epitaxial films grown by low-pressure chemical vapor epitaxy using a new nitrogen source: Hydrazoic acid (HN3)

Abstract

We report results of our growth and characterization of GaN films using low-pressure chemical vapor epitaxy with a new nitrogen source, hydrazoic acid (HN3). This growth technique allows for low-temperature deposition, low III/V ratios, and increased deposition rates (up to ∼2–3 μm/h). The deposited films show Ga:N atomic ratios of 1±0.25 based on our x-ray photoelectron spectroscopy analyses, and the He(II) UPS (ultraviolet photoelectron spectroscopy) spectra compare favorably with the semi-ab initio calculations for the GaN valence bands and with the reported UPS data for single crystal GaN films. X-ray and Raman spectra show deposited films crystallized in the expected wurtzite structure. We find these epitaxial films to be efficient light emitters in the blue or yellow region of the spectrum, depending upon growth conditions. Our photoluminescence time-decay kinetics confirm the excitonic nature of the blue emission. Lastly, far infrared time-domain spectroscopy shows the low carrier concentration of this material.