Enhancement of photoluminescence efficiency from GaN(0001) by surface treatments

Abstract

We investigated the photoluminescence (PL) efficiency of GaN(0001) single crystals with clean and well-defined surfaces using the PL technique in ultrahigh vacuum in situ. We found typical degradation factors: native oxides at the top surface, damaged layers in the subsurface, and hydrogenated non-radiative states inside bulk GaN. By eliminating the degradation factors, a band-to-band PL intensity of approximately 120 times higher than that of the as-received samples was achieved. The PL efficiency enhancement mechanism is discussed, and the role of hydrogen in GaN crystals is proposed.

Effect of H2O intentionally doping on photoelectric properties in MOVPE-growth GaN layers

“…[9][10][11][12][13][14] Hydrogenated states (H -) existing, resulting in a non-radiative process, which weakening the radiative emitting. [19] H 2 O impurity existing in GaN layer, which not only effects electrical properties and but also effects the radiative emission and furthermore effects PL intensity. Hydrogen impurity existing in GaN layer, which not only effects electrical properties and but also effects the radiative emission and futhermore effects PL intensity.…”

“…In the previous study, the species of potential contaminants exist in gaseous sources and their effects on the properties of the epitaxial GaN layer had been discussed. Oxygen, carbon and hydrogen as main unintentional impurity elements were researched [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] . These unintentionally elements in GaN layers could act as donor or acceptor dopants, which may effect the crystal quality, carrier density, carrier mobility and emission efficiency.…”

Effects of intentional oxygen and carbon doping in MOVPE‐grown GaN layers on photoelectric properties

“…Several research groups have carried out theoretical and experimental research on native defect types and defect densities in bulk GaN and the epitaxial GaN layers. Oxygen, carbon, and hydrogen, as primary impurity elements, were analyzed . Among these, oxygen and carbon are generally considered to be shallow donors and deep acceptors at N sites, respectively.…”

“…The previous research studies described in Refs. primarily focused on unintentionally doped GaN layers, in which it is relatively difficult to identify the defect‐related impurity type and impurity concentrations. With increasing NH 3 purity, the detection of the resulting impurity concentrations at the parts per billion (ppb) level becomes more difficult and yet remains absolutely necessary.…”

Modulated optical sensitivity with nanostructured gallium nitride

“…The nanostructured samples were of limited numbers and in order to validate the results, the experiment was repeated. 29 Surface morphology of the three types of samples was evaluated by atomic force microscopy (AFM) using Digital Instrument Nanoscope IIIa in tapping mode and by scanning electron microscopy (SEM). The SEM images of the nanostructure were recorded with a Verios 460L SEM.…”