Direct bandgap photoluminescence from n-type indirect GaInP alloys
Direct bandgap photoluminescence from n-type indirect GaInP alloys
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DOI：
10.1364/prj.5.000239
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发表时间：
2017-06
影响因子：
7.6
通讯作者：
Cong Wang;B. Wang;R. I. Made;S. Yoon;J. Michel
中科院分区：
文献类型：
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作者：
Cong Wang;B. Wang;R. I. Made;S. Yoon;J. Michel
这项工作研究了 Te 掺杂对间接 GaxIn1−xP 合金 (0.72≤x≤0.74) 的直接带隙光致发光 (PL) 的影响。与温度相关的PL表明，由于带隙变窄（BGN）效应，直接Γ谷和间接X谷之间的能量差减小，并且随着温度升高，直接带跃迁逐渐在PL光谱中占主导地位。在 Te 掺杂的 GaxIn1−xP 样品中观察到载流子热化，随着温度从 175 K 升高到 300 K，集成 PL 强度增加。载流子热化的活化能随着掺杂浓度的增加而降低。 BGN 效应和载流子热化都有助于载流子注入 Γ 谷。因此，Te 掺杂的间接 GaxIn1−xP 合金中的直接能带跃迁得到增强。因此，活性掺杂浓度为9×1017 cm−3的Ga0.74In0.26P样品的PL强度比名义上未掺杂样品的PL强度增加了5倍。还发现当掺杂浓度增加到5×1018 cm−3 时，PL 强度显着降低。从横截面透射电子显微镜来看，没有发现大的掺杂剂簇或其他扩展缺陷导致这种退化。
This work studies Te doping effects on the direct bandgap photoluminescence (PL) of indirect GaxIn1−xP alloys (0.72≤x≤0.74). The temperature-dependent PL shows that the energy difference between direct Γ valley and indirect X valleys is reduced due to the bandgap narrowing (BGN) effect, and the direct band transition gradually dominates the PL spectra as temperature increases. Carrier thermalization has been observed for Te-doped GaxIn1−xP samples, as integrated PL intensity increases with increasing temperature from 175 to 300 K. The activation energy for carrier thermalization is reduced as doping concentration increases. Both BGN effect and carrier thermalization contribute to the carrier injection into the Γ valley. As a result, the direct band transition is enhanced in the Te-doped indirect GaxIn1−xP alloys. Therefore, the PL intensity of the Ga0.74In0.26P sample with active doping concentration of 9×1017 cm−3 is increased by five times compared with that of a nominally undoped sample. It is also found that the PL intensity is degraded significantly when the doping concentration is increased to 5×1018 cm−3. From cross-section transmission electron microscopy, no large dopant clusters or other extended defects were found contributing to this degradation.