Electronic and vibronic properties of Mg-doped GaN: The influence of etching and annealing
Tripathy, S. Chua, S.J. Ramam, A. Sia, E.K. Pan, J.S. Lim, R. Yu, G. Shen, Z.X.
Ramam, A.
Sia, E.K.
Pan, J.S.
Lim, R.
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Abstract
We report a systematic study of the effects of wet chemical treatment, inductively coupled plasma etching, and thermal annealing on the surface and optical properties of Mg-doped p-type GaN. The chemical bonding and surface stoichiometry of the GaN surface subjected to different processing steps are analyzed based on the results of x-ray photoelectron spectroscopy. Atomic force microscopy has been employed to characterize the surface morphology. Photoluminescence (PL) and micro-Raman techniques have been used to investigate the electronic and vibrational properties of plasma etched surface. We have correlated the surface changes induced by dry etching of p-type GaN to the corresponding changes in the defect and impurity related states, through their manifestation in the PL spectra. We have observed several local vibrational modes (LVMs) in p-type GaN subjected to various processing steps. A broad structure in the low-temperature Raman spectra around 865cm-1 is attributed to the electronic Raman scattering from neutral Mg acceptors. In addition to the LVMs of Mg-Hn complexes, two new modes near 2405 and 2584cm-1 are observed from the etched p-GaN surface. We have also carried out PL and micro-Raman analyses of Mg-doped GaN films annealed under different conditions. © 2002 American Institute of Physics.
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Journal of Applied Physics
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Date
2002-02-15
DOI
10.1063/1.1446236
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Article