Title: Mg doping of GaN by molecular beam epitaxy
Authors: Lieten, Ruben ×
Motsnyi, V
Zhang, Liyang
Cheng, K
Leys, M
Degroote, S
Buchowicz, G
Dubon, O
Borghs, Gustaaf #
Issue Date: Apr-2011
Publisher: Institute of Physics and IOP Publishing
Series Title: Journal of Physics D, Applied Physics vol:44 issue:13 pages:1-6
Article number: 135406
Abstract: We present a systematic study on the influence of growth conditions on the incorporation and activation of Mg in GaN layers grown by plasma-assisted molecular beam epitaxy. We show that high quality p-type GaN layers can be obtained on GaN-on-silicon templates. The Mg incorporation and the electrical properties have been investigated as a function of growth temperature, Ga : N flux ratio and Mg: Ga flux ratio. It was found that the incorporation of Mg and the electrical properties are highly sensitive to the Ga : N flux ratio. The highest hole mobility and lowest resistivity were achieved for slightly Ga-rich conditions. In addition to an optimal Ga : N ratio, an optimum Mg: Ga flux ratio was also observed at around 1%. We observed a clear Mg flux window for p-type doping of GaN : 0.31% < Mg : Ga < 5.0%. A lowest resistivity of 0.98 Ohmcm was obtained for optimized growth conditions. The p-type GaN layer then showed a hole concentration of 4.3 x 10^17 cm^-3 and a mobility of 15 cm^2 V^-1 s^-1. Temperature-dependent Hall effect measurements indicate an acceptor depth in these samples of 100 meV for a hole concentration of 5.5 x 10^17 cm^-3. The corresponding Mg concentration is 5 x 10^19 cm^-3, indicating approximately 1% activation at room temperature. In addition to continuous growth of Mg-doped GaN layers we also investigated different modulated growth procedures. We show that a modulated growth procedure has only limited influence on Mg doping at a growth temperature of 800 degrees C or higher. This result is thus in contrast to previously reported GaN : Mg doping at much lower growth temperatures of 500 degrees C.
ISSN: 0022-3727
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Solid State Physics and Magnetism Section
Semiconductor Physics Section
× corresponding author
# (joint) last author

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