Photoluminescence band near 2.9 eV in undoped GaN epitaxial layers

The properties of a broad 2.86 eV photoluminescence band in carbon-doped GaN were studied as a function of C-doping level, temperature, and excitation density. The results are consistent with a C Ga -C N deep donor-deep acceptor recombination mechanism as proposed by Seager et al. For GaN:C grown by molecular-beam epitaxy (MBE) the 2.86 eV band is observed in Si co-doped layers exhibiting high n-type conductivity as well as in semi-insulating material. For low excitation density (4 W/cm 2 ) the 2.86 eV band intensity decreases as a function of cw-laser exposure time over a period of many minutes. The transient behavior is consistent with a model based on carrier diffusion and charge trapping-induced Coulomb barriers. The temperature dependence of the blue luminescence below 150 K was different for carbon-contaminated GaN grown by metalorganic vapor phase epitaxy (MOVPE) compared to C-doped MBE GaN.

Section: Discussionmentioning

confidence: 99%

Analysis of the carbon-related “blue” luminescence in GaN

Armitage

Yang

Weber

2005

“…8 That is, the deep center can have its own set of vibrational states, characterized by a local phonon energy E loc . In the simplest form, the energies of these states are given by E 0 ϩ E loc , where E 0 is the ground-state energy and is an integer.…”

Section: Model and Discussionmentioning

confidence: 99%

Fine structure on the green band in ZnO

Reynolds¹,

Jogai²

2001

291

191

An emission band at 2.4 eV, called the green band, is observed in most ZnO samples, no matter what growth technique is used. Sometimes this band includes fine structure, which consists mainly of doublets, repeated with a longitudinal-optical-phonon-energy spacing ͑72 meV͒. We have developed a vibronic model for the green band, based on transitions from two separate shallow donors to a deep acceptor. The donors, at energies 30 and 60 meV from the conduction-band edge, respectively, are also found from Hall-effect measurements.

“…48 Metastable defects are also reported for n-GaN, suggested to be V Ga -related. 49,50 Such defects related to V Ga would be unlikely in p-GaN (Ref. 51) therefore, more work is needed to explore the identity of the metastable defect in Mg-doped GaN.…”

Section: Instabilities Of Acceptor Related Luminescence Spectramentioning

confidence: 99%

Properties of the main Mg-related acceptors in GaN from optical and structural studies

Ḿonemar

Paskov

Pozina

et al. 2014

), the 3.466 eV ABE1 acceptor bound exciton and the associated 3.27 eV donor-acceptor pair (DAP) band are the only strong photoluminescence (PL) signals at 2 K, and are identified as related to the substitutional Mg acceptor with a binding energy of 0.225 6 0.005 eV, and with a moderate phonon coupling strength. Interaction between basal plane stacking faults (BSFs) and Mg acceptors is suggested to give rise to a second deeper Mg acceptor species, with optical signatures ABE2 at 3.455 eV and a corresponding weak and broad DAP peak at about 3.15 eV. The 2.9 eV PL band has been ascribed to many different processes in the literature. It might be correlated with another deep level having a low concentration, only prominent at high Mg doping in material grown by the Metal Organic Chemical Vapor Deposition technique. The origin of the low temperature metastability of the Mg-related luminescence observed by many authors is here reinterpreted and explained as related to a separate non-radiative metastable deep level defect, i.e., not the Mg Ga acceptor. V C 2014 AIP Publishing LLC. [http://dx