Metaferia Wondwosen, Sivakumar Sudhakar, Persson Axel R, Geijselaers Irene, Wallenberg L Reine, Deppert Knut, Samuelson Lars, Magnusson Martin H
NanoLund, Lund University, Box 118, SE-22100, Lund, Sweden. Solid State Physics, Lund University, Box 118, SE-22100, Lund, Sweden.
Nanotechnology. 2018 Jul 13;29(28):285601. doi: 10.1088/1361-6528/aabec0. Epub 2018 Apr 17.
Controlled doping in semiconductor nanowires modifies their electrical and optical properties, which are important for high efficiency optoelectronic devices. We have grown n-type (Sn) doped GaAs nanowires in Aerotaxy, a new continuous gas phase mass production technique. The morphology of Sn doped nanowires is found to be a strong function of dopant, tetraethyltin to trimethylgallium flow ratio, Au-Ga-Sn alloying, and nanowire growth temperatures. High temperature and high flow ratios result in low morphological quality nanowires and in parasitic growth on the wire base and surface. Alloying and growth temperatures of 400 °C and 530 °C, respectively, resulted in good morphological quality nanowires for a flow ratio of TESn to TMGa up to 2.25 × 10. The wires are pure zinc-blende for all investigated growth conditions, whereas nanowires grown by metal-organic vapor phase epitaxy with the same growth conditions are usually mainly Wurtzite. The growth rate of the doped wires is found to be dependent more on the TESn flow fraction than on alloying and nanowire growth temperatures. Our photoluminescence measurements, supported by four-point probe resistivity measurements, reveal that the carrier concentration in the doped wires varies only slightly (1-3) × 10 cm with TESn flow fraction and both alloying and growth temperatures, indicating that good morphological quality wires with high carrier density can be grown with low TESn flow. Carrier concentrations lower than 10 cm can be grown by further reducing the flow fraction of TESn, which may give better morphology wires.
在半导体纳米线中进行可控掺杂可改变其电学和光学性质，这对于高效光电器件而言至关重要。我们采用一种新的连续气相批量生产技术——气相聚合法生长了n型（Sn）掺杂的GaAs纳米线。结果发现，Sn掺杂纳米线的形态强烈依赖于掺杂剂、四乙基锡与三甲基镓的流量比、金 - 镓 - 锡合金化以及纳米线生长温度。高温和高流量比会导致纳米线形态质量较低，并且在线基部和表面出现寄生生长。对于四乙基锡与三甲基镓的流量比高达2.25×10而言，合金化温度和生长温度分别为400℃和530℃时，可得到形态质量良好的纳米线。在所有研究的生长条件下，这些纳米线均为纯闪锌矿结构，而在相同生长条件下通过金属有机气相外延生长的纳米线通常主要是纤锌矿结构。发现掺杂纳米线的生长速率更多地取决于四乙基锡的流量分数，而非合金化和纳米线生长温度。我们的光致发光测量结果，辅以四点探针电阻率测量，表明掺杂纳米线中的载流子浓度随四乙基锡流量分数以及合金化和生长温度的变化仅略有变化（1 - 3）×10 cm，这表明在低四乙基锡流量下可以生长出具有高载流子密度且形态质量良好的纳米线。通过进一步降低四乙基锡的流量分数，可以生长出载流子浓度低于10 cm的纳米线，这可能会得到形态更好的纳米线。
