Department of Physics, University of Southern California, Los Angeles, California 90089, United States.
Nano Lett. 2012 Sep 12;12(9):4484-9. doi: 10.1021/nl301391h. Epub 2012 Aug 20.
We report a systematic study of carrier dynamics in Al(x)Ga(1-x)As-passivated GaAs nanowires. With passivation, the minority carrier diffusion length (L(diff)) increases from 30 to 180 nm, as measured by electron beam induced current (EBIC) mapping, and the photoluminescence (PL) lifetime increases from sub-60 ps to 1.3 ns. A 48-fold enhancement in the continuous-wave PL intensity is observed on the same individual nanowire with and without the Al(x)Ga(1-x)As passivation layer, indicating a significant reduction in surface recombination. These results indicate that, in passivated nanowires, the minority carrier lifetime is not limited by twin stacking faults. From the PL lifetime and minority carrier diffusion length, we estimate the surface recombination velocity (SRV) to range from 1.7 × 10(3) to 1.1 × 10(4) cm·s(-1), and the minority carrier mobility μ is estimated to lie in the range from 10.3 to 67.5 cm(2) V(-1) s(-1) for the passivated nanowires.
我们对 Al(x)Ga(1-x)As 钝化的 GaAs 纳米线中的载流子动力学进行了系统研究。通过钝化，少数载流子扩散长度（L(diff)）从 30nm 增加到 180nm，这是通过电子束感生电流（EBIC）映射测量的，光致发光（PL）寿命从亚 60ps 增加到 1.3ns。在同一根纳米线上，有无 Al(x)Ga(1-x)As 钝化层时，连续波 PL 强度增强了 48 倍，表明表面复合显著减少。这些结果表明，在钝化的纳米线中，少数载流子寿命不受孪晶堆垛层错的限制。根据 PL 寿命和少数载流子扩散长度，我们估计表面复合速率（SRV）范围为 1.7×10(3)至 1.1×10(4)cm·s(-1)，对于钝化的纳米线，少数载流子迁移率μ估计在 10.3 至 67.5cm(2)V(-1)s(-1)范围内。
