Tao Xiaofeng, Jin Xiao, Gao Shiyuan, Yi Xin, Liu Yuchen, Rockett Thomas B O, Bailey Nicholas J, Harun Faezah, Adham Nada A, H Tan Chee, Richards Robert D, David John P R
Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom.
School of Engineering & Physical Sciences, Heriot-Watt's University, Edinburgh EH14 4AS, United Kingdom.
ACS Photonics. 2024 Nov 8;11(11):4846-4853. doi: 10.1021/acsphotonics.4c01343. eCollection 2024 Nov 20.
The presence of large bismuth (Bi) atoms has been shown to increase the spin-orbit splitting energy in bulk GaAsBi, reducing the hole ionization coefficient (β) and thereby reducing the excess noise seen in avalanche photodiodes. In this study, we show that even very thin layers of GaAsBi introduced as quantum wells (QWs) in a GaAs matrix exhibit a significant reduction of β while leaving the electron ionization coefficient, α, largely unchanged. The optical and avalanche multiplication properties of a series of GaAsBi/GaAs multiple quantum well (MQW) p-i-n structures with nominally 5 nm thick, 4.4% Bi GaAsBi QWs, varying from 5 to 63 periods and corresponding barrier widths of 101 to 4 nm were investigated. From photoluminescence, ω-2θ X-ray diffraction, and cross section transmission electron microscopy measurements, the material was found to be of high quality despite the strain introduced by the Bi in all except the samples with 54 and 63 QW periods. Photomultiplication measurements undertaken with different wavelengths showed that α in these MQW structures did not change appreciably with the number of QWs; however, β decreased significantly, especially at lower values, the noise factor, , is reduced by 58% to 3.5 at a multiplication of 10, compared to a similar thickness bulk GaAs structure without any Bi. This result suggests that Bi-containing QWs could be introduced into the avalanching regions of APDs as a way of reducing their excess noise.
已证明，大铋（Bi）原子的存在会增加体相GaAsBi中的自旋轨道分裂能，降低空穴电离系数（β），从而降低雪崩光电二极管中出现的过量噪声。在本研究中，我们表明，即使是在GaAs基体中作为量子阱（QW）引入的非常薄的GaAsBi层，也会使β显著降低，而电子电离系数α基本保持不变。研究了一系列具有标称厚度为5 nm、Bi含量为4.4%的GaAsBi量子阱的GaAsBi/GaAs多量子阱（MQW）p-i-n结构，量子阱周期从5到63个不等，相应的势垒宽度从101到4 nm。通过光致发光、ω-2θ X射线衍射和横截面透射电子显微镜测量发现，除了具有54和63个量子阱周期的样品外，尽管Bi引入了应变，但材料质量仍很高。不同波长下进行的光倍增测量表明，这些MQW结构中的α不会随量子阱数量的变化而明显改变；然而，β显著降低，尤其是在较低值时，与没有任何Bi的类似厚度的体相GaAs结构相比，在倍增为10时，噪声因子降低了58%，降至3.5。这一结果表明，可以将含Bi的量子阱引入雪崩光电二极管的雪崩区域，以降低其过量噪声。
