Effect of GaN cap layer grown at a low temperature on electrical characteristics of Al{sub 0.25}Ga{sub 0.75}N/GaN heterojunction field-effect transistors

Journal Article · Mon Aug 23 04:00:00 EDT 2004 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.1784038· OSTI ID:20632749

Kao, C J; Sheu, J K; Lai, W C; Lee, M L; Chen, M C; Chi, G C ^[1]

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1. Department of Physics, National Central University, Chung-Li 32054, Taiwan (China)

This study examined the effect of GaN grown by metalorganic vapor phase epitaxy at low temperature (LT-GaN) on the surface of Al{sub 0.25}Ga{sub 0.75}N/GaN heterostructures. Depositing a high-resistivity LT-GaN surface layer on the Al{sub 0.25}Ga{sub 0.75}N/GaN heterostructures increased both the sheet carrier concentrations and the electron mobility. This enhancement changed when the LT-GaN high-resistivity layer was removed by high-density-plasma etching. These observations are attributable to the passivation effect, implying that the LT-GaN behaves like a dielectric film, such as silicon dioxide, to passivate the surface states, yielding a different, maybe lower, electronic density of states than that of the Al{sub 0.25}Ga{sub 0.75}N free surface. Hall-effect measurement and gate lag measurement were performed on the field-effect transistor devices to clarify the effect of LT-GaN cap layer on Al{sub 0.25}Ga{sub 0.75}N/GaN heterostructures.

• OSTI ID: 20632749
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 8 Vol. 85; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM NITRIDES
CHEMICAL VAPOR DEPOSITION
DIELECTRIC MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRON MOBILITY
ETCHING
FIELD EFFECT TRANSISTORS
GALLIUM NITRIDES
HALL EFFECT
HETEROJUNCTIONS
PASSIVATION
PLASMA DENSITY
SEMICONDUCTOR MATERIALS
SILICON OXIDES
THIN FILMS
VAPOR PHASE EPITAXY