Exciton localization on basal stacking faults in a-plane epitaxial lateral overgrown GaN grown by hydride vapor phase epitaxy
We present a detailed study of the luminescence at 3.42 eV usually observed in a-plane epitaxial lateral overgrowth (ELO) GaN grown by hydride vapor phase epitaxy on r-plane sapphire. This band is related to radiative recombination of excitons in a commonly encountered extended defect of a-plane GaN: I-1 basal stacking fault. Cathodoluminescence measurements show that these stacking faults are essentially located in the windows and the N-face wings of the ELO-GaN and that they can appear isolated as well as organized into bundles. Time-integrated and time-resolved photoluminescence, supported by a qualitative model, evidence not only the efficient trapping of free excitons (FXs) by basal plane stacking faults but also some localization inside I-1 stacking faults themselves. Measurements at room temperature show that FXs recombine efficiently with rather long luminescence decay times (360 ps), comparable to those encountered in high-quality GaN epilayers. We discuss the possible role of I-1 stacking faults in the overall recombination mechanism of excitons.
Keywords: cathodoluminescence ; excitons ; gallium compounds ; III-V semiconductors ; photoluminescence ; sapphire ; semiconductor epitaxial layers ; semiconductor growth ; stacking faults ; time resolved spectra ; vapour phase epitaxial growth ; wide band gap semiconductors ; Multiple-Quantum Wells ; Optical-Properties ; Heterostructures ; Semiconductors ; Luminescence ; Emissions
Record created on 2009-03-01, modified on 2016-08-08