High Resistivity AlxGa1-xN Layers Grown by MOCVD
A. Y. Polyakov, M. Shin
Department of Materials Science and Engineering, Carnegie Mellon University
D. W. Greve
Department of Electrical and Computer Engineering, Carnegie Mellon University
M. Skowronski
Department of Materials Science and Engineering, Carnegie Mellon University
R. G. Wilson
Hughes Research Laboratory
This article was received on May 25, 1996 and
accepted on November 15, 1996. Abstract
Undoped AlxGa1-xN layers with good surface
morphology and very low electron concentration have been grown by MOCVD on
sapphire substrates. The observed electrical and optical properties depend
strongly on the growth temperature. Layers grown at 1000 °C exhibited
low resistivity and strong optical absorption below the bandgap. In
contrast,layers grown at 1050 °C had low carrier concentrations and good
mobilities. Virtually no optical absorption near the band edge was observed as
opposed to the usual situation in AlxGa1-xN. The
electrical properties of these layers can be explained by the presence of donor
centers whose energy increases with composition, and deeper lying compensating
defects. The interaction of these centers renders the samples with x<0.2
highly resistive, with room temperature resistivity higher than 106
ohm-cm. SIMS data strongly suggest that the electrically active centers in our
AlGaN layers are native defect-related. Implantation of Si ions into
Al0.12Ga0.88N, and subsequent annealing at 1140 °C
resulted in layers with electron concentration of 4.6 x 1017
cm-3.Outline
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 1, 36(1996).
last updated October 30, 1997 11:33:48 AM.© 1996-1997 The Materials Research Society
