Nature of the 2.8 eV photoluminescence band in Mg doped GaN

Abstract

The blue Mg induced 2.8 eV photoluminescence (PL) band in metalorganic chemical vapor deposition grown GaN has been studied in a large number of samples with varying Mg content. It emerges near a Mg concentration of 1x10(exp 19) cm(-3) and at higher concentrations dominates the room temperature PL spectrum. The excitation power dependence of the 2.8 eV band provides convincing evidence for its donor-acceptor (D-A) pair recombination character. It is suggested that the acceptor A is isolated Mg(Ga) while the spatially separated, deep donor (430 meV) D is attributed to a nearest-neighbor associate of a Mg(Ga) acceptor with a nitrogen vacancy, formed by self-compensation

Properties of GaN epitaxial layers grown on 6H-SiC(0001) by plasma-assisted molecular beam epitaxy

“…Donor-acceptor (D-A) features are seen in the range 3.1-3.3 eV, and deep luminescence bands are seen near 2.8 eV (blue luminescence, BL) and 2.2 eV (yellow luminescence, YL). We tentatively associate the 2.8 eV band with intrinsic defects such as N vacancies, as seen in Mg-containing material [20], although we do note the similarity of this band with one previously reported in GaN films and attributed to D-A transitions in the SiC substrates [21]. The 2.2 eV band is commonly observed in GaN prepared under a broad range of conditions.…”

Optical study of the band structure of wurtzite GaP nanowires

“…35 Furthermore, we observe a strong blue shift ($5 meV/decade) with increasing excitation power, which is typical for a DAP transition, due to Coulomb interactions between charged donors and acceptors. 36,37 Additional narrow peaks are visible in the energy range below the a-line in Fig. 3(a).…”

“…36,37 First, the 2.088 eV emission line is asymmetrically broadened with a FWHM of $30 meV, with the presence of LO/TO phonon replicas. 47 Second, both D 0 1 A 0 1 and D 0 2 A 0 2 peaks show a strong blue shift of the emission energy ($5 meV/decade) with increasing excitation power (see Fig.…”

Thermal admittance spectroscopy of Mg-doped GaN Schottky diodes

“…4 Photoluminescence studies of the donor-acceptor recombination yield again a different set of values between 150 and 250 meV. [10][11][12][13][14] The thermal capture cross section of the A level of 2ϫ10 Ϫ19 cm 2 is close to the value given by admittance spectroscopy in Ref. 4.…”

“…The activation energy of the acceptor level related to the magnesium atoms has been measured by various experimental techniques leading to values between 70 and 250 meV, [2][3][4][5][6][7][8][9][10][11][12][13][14] which is much larger than for the impurities generally used as shallow dopants. As a consequence, Mg is not fully ionized at any temperature, and the resulting hole concentration is strongly temperature dependent.…”