光致发光
光致发光激发
带隙
谱线
激发
吸收(声学)
能量(信号处理)
外延
材料科学
物理
凝聚态物理
光学
纳米技术
图层(电子)
量子力学
作者
J. Bleuse,Sylvain Perret,Yoann Curé,Louis Grenet,Régis André,H. Mariette
出处
期刊:Physical review
日期:2020-11-19
卷期号:102 (19)
被引量:7
标识
DOI:10.1103/physrevb.102.195205
摘要
We report on the precise determination, in ${\mathrm{Ag}}_{2}\mathrm{Zn}\mathrm{Sn}{\mathrm{Se}}_{4}$ epitaxial layer, of both the band gap ${E}_{\text{g}}$ and the characteristic Urbach energy $U$ that describes the density of localized, defect states in the gap. Various origins for these defect band tail states have been considered, together with the corresponding modeling for their density of states, in order to fit the whole of the optical spectral data. The interest of the methodology developed here is to account quantitatively not only for the absorption and steady-state photoluminescence data but also for the time-resolved photoluminescence spectra. We compare the different origins of localized band tail states to select the standard textbook, Urbach tail model that corresponds to short-range band gap fluctuations. Such an approach is different from the one most often used to evaluate the energy extent of the localized states, which is the Stokes shift between the energies of the photoluminescence emission and the absorption threshold. The advantage of the present method is that no arbitrary choice of the low power excitation has to be done to select the photoluminescence emission spectrum and its peak energy. Thanks to this systematic study of both photoluminescence excitation and time-resolved photoluminescence spectra at low temperature (6 K), the values ${E}_{\text{g}}=1226\ifmmode\pm\else\textpm\fi{}5$ meV and $U=20\ifmmode\pm\else\textpm\fi{}3$ meV are found for this promising absorber for thin films photovoltaics.
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