NanoLund and Division of Chemical Physics, Lund University , Box 124, 221 00 Lund, Sweden.
NanoLund and Division of Solid State Physics, Lund University , Box 118, 221 00 Lund, Sweden.
Nano Lett. 2017 Jul 12;17(7):4248-4254. doi: 10.1021/acs.nanolett.7b01159. Epub 2017 Jun 30.
Understanding of recombination and photoconductivity dynamics of photogenerated charge carriers in GaInP NWs is essential for their optoelectronic applications. In this letter, we have studied a series of GaInP NWs with varied Ga composition. Time-resolved photoinduced luminescence, femtosecond transient absorption, and time-resolved THz transmission measurements were performed to assess radiative and nonradiative recombination and photoconductivity dynamics of photogenerated charges in the NWs. We conclude that radiative recombination dynamics is limited by hole trapping, whereas electrons are highly mobile until they recombine nonradiatively. We also resolve gradual decrease of mobility of photogenerated electrons assigned to electron trapping and detrapping in a distribution of trap states. We identify that the nonradiative recombination of charges is much slower than the decay of the photoluminescence signal. Further, we conclude that trapping of both electrons and holes as well as nonradiative recombination become faster with increasing Ga composition in GaInP NWs. We have estimated early time electron mobility in GaInP NWs and found it to be strongly dependent on Ga composition due to the contribution of electrons in the X-valley.
了解 GaInP NWs 中光生载流子的复合和光电导动力学对于它们的光电应用至关重要。在这封信件中，我们研究了一系列具有不同 Ga 组成的 GaInP NWs。通过进行时间分辨光致发光、飞秒瞬态吸收和时间分辨太赫兹传输测量，评估了 NWs 中光生电荷的辐射复合和非辐射复合以及光电导动力学。我们得出结论，辐射复合动力学受到空穴捕获的限制，而电子在非辐射复合之前具有很高的迁移率。我们还解析出，由于在陷阱态分布中电子的捕获和去捕获，光生电子的迁移率逐渐下降。我们确定，电荷的非辐射复合比光致发光信号的衰减要慢得多。此外，我们得出结论，随着 GaInP NWs 中 Ga 组成的增加，电子和空穴的捕获以及非辐射复合都会变得更快。我们已经估计了 GaInP NWs 中早期的电子迁移率，并发现由于 X 谷中电子的贡献，它强烈依赖于 Ga 组成。
