| AVS 59th Annual International Symposium and Exhibition | |
| Electronic Materials and Processing | Thursday Sessions |
| Session EM+TF+AS-ThA |
| Session: | Growth and Characterization of Group III-Nitride Materials |
| Presenter: | M.K.I. Senevirathna, Georgia State University |
| Authors: | M.K.I. Senevirathna, Georgia State University S.D. Gamage, Georgia State University R. Atalay, Georgia State University R.L. Samaraweera, Georgia State University A.G.U. Perera, Georgia State University B. Kucukgok, University of North Carolina at Charlotte A.G. Melton, University of North Carolina at Charlotte I. Ferguson, University of North Carolina at Charlotte N. Dietz, Georgia State University |
| Correspondent: | Click to Email |
The influence of the substrate growth temperature on the structural and optoelectronic properties of group III-nitride layers grown by various growth techniques has been extensively studied and reported on, due to the close relationship of substrate temperature with crystalline quality and the point defect chemistry of the alloy. Most thin film growth systems only control the substrate temperature and have limited control to adjust the gas phase decomposition dynamic independent to influence to growth surface chemistry.
In this contribution, we present results on the growth of InN epilayers grown the high-pressure chemical vapor deposition (HPCVD), studying in influence of and independent from the substrate temperature controlled gas phase temperature above the substrate reactor zone. The HPCVD reactor system has two heater elements: one that controls the substrate temperature and a second radiative heat source above, which allows the control of the gas phase temperature. While the substrate temperature dominantly controls the growth process and the crystalline layer properties, the heater above the substrate surface influences strongly the precursor decomposition processes and the diffusion and concentrations of the precursor fragments in the boundary layer and at the growth surface. InN epilayers grown with different gas phase heating settings where grown and analyzed with the respect to their short- and long-range crystalline ordering and their optoelectronic properties as function of the gas phase temperature. The long-range and the short-range crystalline order of the layers have been analyzed by x-ray diffraction 2Θ-ω scans FWHM and the Raman E2 (high) FWHM, respectively. The optoelectronic properties have been studied by reflectance spectroscopy and are related to the structural properties and the additional gas phase heating.
The figure depicts the FWHM values of Raman-E2 (high) peak of the InN epilayers as a function of reactor pressure for higher (red line) and lower (blue line) gas phase temperature. The results indicate that there is an improvement of the short-range crystalline order of the layers with lower gas phase temperature. However, the FWHM values of XRD 2Θ-ω scans, which are not shown here, are indicating that there is an improvement of long-range crystalline order of the layers with increasing gas phase heating.