Doped GaN nanowires on diamond: Structural properties and charge carrier distribution

Journal Article · Wed Jan 28 00:00:00 EST 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4906747· OSTI ID:22413001

Schuster, Fabian; Winnerl, Andrea; Weiszer, Saskia; Hetzl, Martin; Garrido, Jose A.; Stutzmann, Martin ^[1]

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1. Walter Schottky Institut and Physik Department, Technische Universität München, Am Coulombwall 4, 85748 Garching (Germany)

In this work, we present a detailed study on GaN nanowire doping, which is vital for device fabrication. The nanowires (NWs) are grown by means of molecular beam epitaxy on diamond (111) substrates. Dopant atoms are found to facilitate nucleation, thus an increasing NW density is observed for increasing dopant fluxes. While maintaining nanowire morphology, we demonstrate the incorporation of Si and Mg up to concentrations of 9× 10{sup 20}cm{sup −3} and 1 × 10{sup 20}cm{sup −3}, respectively. The dopant concentration in the nanowire cores is determined by the thermodynamic solubility limit, whereas excess dopants are found to segregate to the nanowire surface. The strain state of the NWs is investigated by X-ray diffraction, which confirms a negligible strain compared to planar thin films. Doping-related emissions are identified in low-temperature photoluminescence spectroscopy and the temperature quenching yields ionization energies of Si donors and Mg acceptors of 17 meV and 167 meV, respectively. At room temperature, luminescence and absorption spectra are found to coincide and the sub-band gap absorption is suppressed in n-type NWs. The charge carrier distribution in doped GaN nanowires is simulated under consideration of surface states at the non-polar side facets. For doping concentrations below 10{sup 17}cm{sup −3}, the nanowires are depleted of charge carriers, whereas they become highly conductive above 10{sup 19}cm{sup −3}.

• OSTI ID: 22413001
• Journal Information: Journal of Applied Physics, Vol. 117, Issue 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTRA
CHARGE CARRIERS
COMPARATIVE EVALUATIONS
CONCENTRATION RATIO
DIAMONDS
DOPED MATERIALS
EMISSION SPECTROSCOPY
GALLIUM NITRIDES
IONIZATION
MOLECULAR BEAM EPITAXY
MORPHOLOGY
NANOWIRES
NUCLEATION
PHOTOLUMINESCENCE
STRAINS
SUBSTRATES
SURFACES
TEMPERATURE DEPENDENCE
THIN FILMS
X-RAY DIFFRACTION