AVS 59th Annual International Symposium and Exhibition
    Electronic Materials and Processing Thursday Sessions
       Session EM+TF+AS-ThA

Paper EM+TF+AS-ThA11
Dependence of Gallium Incorporation and Structural Properties of Indium-rich InxGa1-xN Epilayers on Ammonia - MO Precursor Pulse Separation

Thursday, November 1, 2012, 5:20 pm, Room 14

Session: Growth and Characterization of Group III-Nitride Materials
Presenter: S.D. Gamage, Georgia State University
Authors: S.D. Gamage, Georgia State University
R. Atalay, Georgia State University
M.K.I. Senevirathna, Georgia State University
R.L. Samaraweera, Georgia State University
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 large band gap tunability of ternary InxGa1-xN alloys has opened new avenues in the field of advanced optoelectronics devices fabrication. However, the growth process of the epilayers of these materials is yet to be well explored. In this contribution, the growth of InxGa1-xN epilayers under super atmospheric pressure is studied. In order to mitigate the gas phase reactions and the gap of dissociation temperatures between the binary alloys GaN and InN, and to improve the phase stability, high growth chamber pressure has been used together with a pulsed precursor injection system. This pulsed precursor injection scheme introduces two important process parameters; the precursor separation times between the metal organic (MO) sources (TMI and TMG) and ammonia (S1), and ammonia and MO (S2).

With the aim to find the optimum S2 separation for high quality indium-rich InGaN epilayers, a set of InxGa1-xN samples with nominal x=0.9 has been grown with different S2 timings. It will be shown that the S2 separation is critical for the incorporation of gallium into the epilayers. In order to maintain single-phase epilayers, the S2 separation has to be increased from S2=400 ms for InN to over 1200 ms for InxGa1-xN. Raman spectroscopy and X-ray diffraction (XRD) spectroscopy are used to study the structural properties while the Fourier Transform Infra-red (FTIR) and transmission spectroscopy are utilized to investigate the electrical and optical properties of the epilayers.