Modification of carrier localization in basal‐plane stacking faults: The effect of Si‐doping in a‐plane GaN

Abstract

AbstractThe optical properties of Si‐doped a‐plane GaN epilayers grown on r‐plane sapphire are studied. The low temperature emission is dominated by basal‐plane stacking fault (BSF) recombination throughout the investigated doping range (1 × 1017 to 5 × 1019 cm−3). From temperature dependent photoluminescence (PL) measurements in conjunction with PL excitation studies, the carrier localization energy within the BSF is inferred to decrease from 17 meV to a negligible level as the doping density increases from 1 × 1017 to 5 × 1018 cm−3. It is proposed that electrons, ionized from the Si‐donor atoms at the growth temperature, are able to transfer to the BSFs, where they progressively fill the available density of localized states. For doping levels in excess of 1 × 1018 cm−3, the luminescence linewidth broadens significantly and the luminescence transients decay with a single exponential time constant. This behaviour is attributed to the onset of band‐filling which causes a marked increase in the free electron density within the BSFs.