Substrate nitridation induced modulations in transport properties of wurtzite GaN/p-Si (100) heterojunctions grown by molecular beam epitaxy

Journal Article · Tue Nov 01 00:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3658867· OSTI ID:22038759

Bhat, Thirumaleshwara N; Rajpalke, Mohana K; Krupanidhi, S B ^[1]; Roul, Basanta; Kumar, Mahesh ^[1]

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1. Materials Research Centre, Indian Institute of Science, Bangalore- 560012 (India)

Phase pure wurtzite GaN films were grown on Si (100) substrates by introducing a silicon nitride layer followed by low temperature GaN growth as buffer layers. GaN films grown directly on Si (100) were found to be phase mixtured, containing both cubic ({beta}) and hexagonal ({alpha}) modifications. The x-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy studies reveal that the significant enhancement in the structural as well as in the optical properties of GaN films grown with silicon nitride buffer layer grown at 800 deg. C when compared to the samples grown in the absence of silicon nitride buffer layer and with silicon nitride buffer layer grown at 600 deg. C. Core-level photoelectron spectroscopy of Si{sub x}N{sub y} layers reveals the sources for superior qualities of GaN epilayers grown with the high temperature substrate nitridation process. The discussion has been carried out on the typical inverted rectification behavior exhibited by n-GaN/p-Si heterojunctions. Considerable modulation in the transport mechanism was observed with the nitridation conditions. The heterojunction fabricated with the sample of substrate nitridation at high temperature exhibited superior rectifying nature with reduced trap concentrations. Lowest ideality factors ({approx}1.5) were observed in the heterojunctions grown with high temperature substrate nitridation which is attributed to the recombination tunneling at the space charge region transport mechanism at lower voltages and at higher voltages space charge limited current conduction is the dominating transport mechanism. Whereas, thermally generated carrier tunneling and recombination tunneling are the dominating transport mechanisms in the heterojunctions grown without substrate nitridation and low temperature substrate nitridation, respectively.

• OSTI ID: 22038759
• Journal Information: Journal of Applied Physics, Vol. 110, Issue 9; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
FILMS
GALLIUM NITRIDES
HETEROJUNCTIONS
LAYERS
MODULATION
MOLECULAR BEAM EPITAXY
NITRIDATION
OPTICAL PROPERTIES
PHOTOELECTRON SPECTROSCOPY
PHOTOLUMINESCENCE
RECOMBINATION
SCANNING ELECTRON MICROSCOPY
SEMICONDUCTOR MATERIALS
SILICON NITRIDES
SPACE CHARGE
SUBSTRATES
TRAPS
TUNNEL EFFECT
X-RAY DIFFRACTION