| AVS 59th Annual International Symposium and Exhibition | |
| Electronic Materials and Processing | Thursday Sessions |
| Session EM-ThP |
| Session: | Electronic Materials and Processing Poster Session |
| Presenter: | R. Atalay, Georgia State University |
| Authors: | R. Atalay, Georgia State University M. Buegler, Technische Universität Berlin, Germany S.D. Gamage, Georgia State University M.K.I. Senevirathna, Georgia State University G. Durkaya, University of California Irvine L. Su, UNC Charlotte A.G.U. Perera, Georgia State University I. Ferguson, UNC Charlotte N. Dietz, Georgia State University |
| Correspondent: | Click to Email |
Over the last two decades, significant research efforts have been devoted to understand and improve the physical properties of InN epilayers. However, even today, there is still a significant lack of understanding how the different partial pressures of the precursor fragments of trimethylindium and ammonia affect the InN surface and growth chemistry and influence the materials properties.
In this study, high-pressure chemical vapor deposition (HPCVD) is used to control and suppress the disassociation of InN alloys at higher growth temperatures, together with a pulsed precursor injection approach to reduce gas phase reactions and to control the surface chemistry. In this contribution, we will present results on the influence of the group V/III molar precursor ratio on the structural and optoelectronic properties of InN epilayers grown on sapphire substrate with a reactor pressure of 8 bar. The group V/III molar precursor ratio was studied in molar V/III-ratio range of 900 to 3600. The structural analysis show for molar V/III-ratio of 2400 an optimum with, Raman and XRD having the lowest FWHM of 7.53 cm-1 and 210 arcsec, respectively. The XRD results indicate improved grain size and reduced strain effect. Optical FTIR reflectance analysis of this epilayer found a free carrier concentration of 1.7×1018 cm-3, a mobility of 1020 cm2 V-1 s-1 and a growth rate of 120 nm/h. The Raman analysis for these epilayers indicate that the non-polar phonon frequency with symmetry of E2 is changes little within the studied molar V/III precursor ratio range; however, the polar phonon modes of both transverse optical (TO) and longitudinal optical (LO) are affected significantly. The studies showed also reveal that LO-phonon is influenced from the free carrier concentration (ne) and TO-phonon is influenced from the free carrier mobility (μ). In addition, surface morphology studies by AFM show an improved average grain size of 8.51×10-2 μm2 for the m olar V/III-ratio of 2400.