期刊
APPLIED PHYSICS LETTERS
卷 94, 期 16, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.3122934
关键词
adsorption; electron density; gallium compounds; III-V semiconductors; photoluminescence; photon stimulated desorption; surface photovoltage; surface states; wide band gap semiconductors
资金
- National Science Foundation
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [0804679] Funding Source: National Science Foundation
The effect of an ambient environment on the surface photovoltage and photoluminescence observed for GaN is studied. In air ambient the upward band bending gradually increases under UV illumination and is explained by the photoinduced chemisorption of surface adsorbates. Specifically, the increase in negative surface charge is consistent with the transfer of electrons from surface states or bulk to oxygen species physisorbed at the GaN surface. In contrast, the upward band bending gradually decreases in vacuum under UV illumination and can be explained by the photoinduced desorption of these species. The photoadsorption and photodesorption of negatively charged species cause the surface depletion region to increase and decrease, respectively. This change in depletion region width is consistent with the observed decrease in photoluminescence intensity in air ambient and its significant increase in vacuum for a sample with low free electron concentration.
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