Photoluminescence study of GaAsSbN bulk epilayers on GaAs substrates
Date Issued
2007
Date
2007
Author(s)
Chen, Tsung-Yi
DOI
zh-TW
Abstract
The photoluminescence (PL) properties of dilute nitride GaAsSbN bulk epilayers are investigated. The GaAsSbN samples were grown on GaAs substrates by gas-source molecular beam epitaxy and characterized after a thermal annealing at 800℃ for 5 min. The main PL peak energy of all the samples shows “S-shape” behavior in the low temperature region, which is attributed to the behavior of the emission from band-tail states, and fits the empirical Varshni curve in the high temperature region, which evidences the band edge luminescence, in the temperature-dependent measurement. Samples grown at 490℃ are with more significant “S-shape” behavior than the ones grown at low temperature, indicating the worse compositional homogeneity in the former samples. Through a comparison between the room temperature PL energy and the GaAsSb energy gap reported in literatures, we found that the energy reduction due to nitrogen incorporation in GaAsSbN is independent of the Sb composition, implying that the energy positions of the conduction and valence band can be independently controlled by N and Sb composition respectively. We also found that the Varshni parameters of all the samples are close to those of GaAsN with similar N composition. Beside the main peak, a broad deep PL emission peaking at ~0.7eV was also observed in most of the samples. The Arrhenius activation energies of the PL intensity were investigated. The activation energy of the band-tail emission fits their dissociation temperature quite well. For band edge luminescence at high temperature, we use a configuration-coordinate model, which is considered to be related to the deep level emission, to explain its activation energy successfully. Among the epilayers grown coherently on the GaAs substrate, the lowest room temperature PL energy is 0.84 eV. This result suggests that GaAsSbN is a promising material for GaAs-based long wavelength optoelectronic devices and tandem solar cells.
Subjects
砷銻氮化鎵
光激發螢光
變溫PL
瓦希尼
活化能
GaAsSbN
Photoluminescence
temperature-dependent PL
Varshini
activation energy
Type
thesis
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