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Band bending near the surface in GaN as detected by a charge sensitive probe

Published online by Cambridge University Press:  01 February 2011

S. Sabuktagin ,
M. A. Reshchikov ,
D. K. Johnstone  and
H. Morkoç
S. Sabuktagin
Affiliation:
Department of Electrical Engineering and Physics Department, Virginia Commonwealth University, Richmond, VA 23284
M. A. Reshchikov
Affiliation:
Department of Electrical Engineering and Physics Department, Virginia Commonwealth University, Richmond, VA 23284
D. K. Johnstone
Affiliation:
Department of Electrical Engineering and Physics Department, Virginia Commonwealth University, Richmond, VA 23284
H. Morkoç
Affiliation:
Department of Electrical Engineering and Physics Department, Virginia Commonwealth University, Richmond, VA 23284
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Abstract

We measured the absolute value of the surface band bending in GaN layers grown by molecular beam epitaxy with a charge sensitive surface microprobe. Surface potential measurements showed an upward band bending from 0.7 to 1.4 eV in undoped and Si-doped GaN. The samples stored in dark for one week showed an increase in band bending by up to 0.1 eV. The effect of ultraviolet (UV) exposure (with a lamp or a pulsed nitrogen laser) on band bending was also studied. Typically, the surface barrier decreased by about 0.2 – 0.5 eV under UV light. The barrier was restored very slowly (by a logarithmic law) in the dark at room temperature. These and other similar phenomena are tentatively attributed to thermionic transfer of free electrons from the bulk to the surface states. Photo-induced desorption of oxygen may also play a role in the observed effects.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 798: Symposium Y – GaN and Related Alloys , 2003 , Y5.39
Copyright
Copyright © Materials Research Society 2004

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References

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