Optical characterization of InN layers grown by high-pressure chemical vapor deposition

Abstract

The optical properties of InN layers grown by high-pressure chemical vapor deposition have been studied. Raman, infrared reflection, and transmission spectroscopy studies have been carried out to investigate the structural and optical properties of InN films grown on sapphire and GaN/sapphire templates. Results obtained from Raman and IR reflectance measurements are used to estimate the free carrier concentrations, which were found to be varying from mid 1018 to low 1020cm−3. The values for free carrier concentrations are compared to optical absorption edge estimates obtained from optical transmission spectra analysis. The analysis shows that optical absorption edge for InN shifts below 1.1eV as the free carrier concentration decreases to low 1018cm−3.

Comparative study on structural and optical properties of nitrogen rich InN on Si(110) and 6H-SiC

“…The obtained values are comparable to the reported values for wurtzite InN. 28 Since the spectral strength of A 1 (LO) phonon mode of InN is weak in nature as compared to E 1 (TO) mode, it cannot be clearly seen in the FTIR reflectance spectrum. Nevertheless, the mode due to A 1 (LO) is very obvious in the Raman spectrum (will be discussed later).…”

Generation of InN nanocrystals in organic solution through laser ablation of high pressure chemical vapor deposition-grown InN thin film

“…However, high equilibrium vapor pressure of nitrogen and low decomposition temperature of InN make the synthesis of high quality InN thin films quite challenging at low pressures (Davydov and Klochikhin 2004;Butcher and Tansley 2005). The influence of growth pressure on InN films have been studied by Dietz et al and they have reported superior quality InN films grown at high temperatures, which are at least 200°C higher compared to InN films grown at low pressures (Alevli et al 2006(Alevli et al , 2008Dietz et al 2008). They achieved the growth of good quality InN films utilizing a novel high pressure chemical vapor deposition (HPCVD) system which enables the researchers to control the vastly different partial pressures of the constituents involved in the growth process and stabilize the InN films at elevated temperatures (Alevli et al 2006).…”

Substrate temperature influence on the properties of GaN thin films grown by hollow-cathode plasma-assisted atomic layer deposition

“…Figure 5 shows the optical transmission spectra of GaN layers together with the calculated spectra. The optical transmission spectra were fitted by applying a model dielectric function (MDF) 7 with additional oscillators. This approach provided a good fit of experimental transmission spectra, where the MDF is defined as…”

“…Moreover, the integration of narrow band gap (In-rich) with wide band gap (Ga-rich) III-nitride layers is not possible due to the low vapor pressure and disassociation temperature of InN. 7 This restricts the development of highly efficient III-nitride multijunction solar cells and spectral tunable light sources. In order to overcome the limitations due to high substrate temperatures, most prominent alternative approaches for low-temperature growth of GaN include physical vapor deposition techniques (sputtering and pulsed laser deposition) as well as a chemical vapor deposition technique: plasma-assisted atomic layer deposition (PA-ALD).…”