Yellow Band and Deep levels in Undoped MOVPE GaN.
F. J. Sánchez, D. Basak, M. A. Sánchez-García, E. Calleja, E. Muñoz, I. Izpura, F. Calle, J. M. G. Tijero
Dpt. Ingeniería Electrónica, E.T.S.I. Telecomunicación, Politécnica, Ciudad Universitaria
B. Beaumont, P. Lorenzini, Pierre Gibart
Centre de Recherche sur l'Hetero-Epitaxie et ses Applications, CRHEA-CNRS
T. S. Cheng, C. T. Foxon
Department of Physics, University of Nottingham
J. W. Orton
Department of Electrical and Electronic Engineering, University of Nottingham
This article was received on June 4, 1996 and
accepted on September 9, 1996. Abstract
Undoped layers of GaN grown by MOVPE on sapphire substrates have been
characterized by photoluminescence, photocapacitance and photoinduced current
transient spectroscopy (PICTS). Photocapacitance reveals in all samples two
specific signatures at photon energies of 1 eV and 2.5 eV. The photocapacitance
decrease observed at 1 eV seems to be due to an electron capture process from
the valence band, whereas the capacitance increase at 2.5 eV is related to an
electron emission process. The fact that the capacitance step at 1 eV is only
seen after photoionization at energies above 2.5 eV, and the observed
correlation between its amplitude and the photoluminescence intensity of the
"yellow band", lead us to conclude that both transitions are linked
to the same trap, which is also suggested to be responsible for the yellow
band. The position of this trap, at 2.5 eV below the conduction band, is
confirmed by PICTS measurements, that show a hole thermal emission activation
energy of 0.9 eV at 350 K.Outline
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 1, 7(1996).
last updated October 29, 1997 10:22:22 AM.© 1996-1997 The Materials Research Society
