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Two charge states of the C N acceptor in GaN: Evidence from photoluminescence

2018; American Physical Society; Volume: 98; Issue: 12 Linguagem: Inglês

10.1103/physrevb.98.125207

2469-9977

M. A. Reshchikov, Mykhailo Vorobiov, D. O. Demchenko, Ümit Özgür, H. Morkoç̌, A. G. Lesnik, Marc P. Hoffmann, Florian Hörich, A. Dadgar, A. Strittmatter,

ZnO doping and properties

We have found a photoluminescence (PL) band with unusual properties in GaN. The blue band, termed as the ${\mathrm{BL}}_{C}$ band, has a maximum at about 2.9 eV and an extremely short lifetime (shorter than 1 ns for a free-electron concentration of about ${10}^{18}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$). The electron- and hole-capture coefficients for this defect-related band are estimated as ${10}^{\ensuremath{-}9}$ and ${10}^{\ensuremath{-}10}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{3}/\mathrm{s}$, respectively. The ${\mathrm{BL}}_{C}$ band is observed only in GaN samples with relatively high concentration of carbon impurity, where the yellow luminescence (the YL1 band) with a maximum at 2.2 eV is the dominant defect-related PL. Both the YL1 and ${\mathrm{BL}}_{C}$ bands likely originate from the ${\mathrm{C}}_{\mathrm{N}}$ defect, namely, from electron transitions via the $\ensuremath{-}/0$ and $0/+$ thermodynamic transition levels of the ${\mathrm{C}}_{\mathrm{N}}$. The ${\mathrm{BL}}_{C}$ band appears only at high excitation intensities in $n$-type GaN samples codoped with Si and C, and it can be found in a wide range of excitation intensities in semi-insulating (presumably $p$-type) GaN samples doped with C. The properties and behavior of the YL1 and ${\mathrm{BL}}_{C}$ bands can be explained using phenomenological models and first-principles calculations.