Perturbation of charges in AlGaN/GaN heterostructures by ultraviolet laser illumination

Journal Article · Fri Oct 15 04:00:00 EDT 2004 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1794892· OSTI ID:20662109

Koley, G; Cha, Ho-Young; Hwang, Jeonghyun; Schaff, W J; Eastman, L F; Spencer, M G ^[1]

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1. Department of Electrical Engineering, University of South Carolina, Columbia, South Carolina 29208 (United States)

Perturbation of charges in AlGaN/GaN heterostructures by ultraviolet (UV) laser illumination has been studied by Kelvin probe microscopy. It is observed that the charge dipole formed across the AlGaN barrier decreases under UV laser illumination, and typically takes a few days to a few weeks to revert back to the original equilibrium value. Bare surface barrier height of AlGaN/GaN heterostructures has been calculated based on the observed recovery transients after the UV illumination is switched off, and found to increase with Al alloy composition as well as thickness of the AlGaN layer. After SiN{sub x} passivation, the surface barrier is reduced, and the charges cannot be perturbed to a significant extent. It is further observed that by UV illumination through a quartz mask, surface barrier patterns can be imprinted on AlGaN/GaN heterostructures, which stay for several hours to several days. It is proposed that the imprinted patterns, with a spatial resolution {approx}1-2 {mu}m, are caused by surface trapping of photogenerated holes.

• OSTI ID: 20662109
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 96; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ALUMINIUM COMPOUNDS
DIPOLES
DISTURBANCES
GALLIUM NITRIDES
HETEROJUNCTIONS
HOLE MOBILITY
HOLES
ILLUMINANCE
LASERS
MICROSCOPY
PASSIVATION
QUARTZ
SEMICONDUCTOR MATERIALS
SILICON COMPOUNDS
SPATIAL RESOLUTION
SURFACE POTENTIAL
SURFACES
THICKNESS
TRAPPING
ULTRAVIOLET RADIATION