The realization of n-type conduction in directly bottom-up grown Si-doped GaAs nanowires (NWs) by molecular beam epitaxy has remained a long-standing challenge. Unlike the commonly employed vapor–liquid−solid growth, where the amphoteric nature of Si dopants induces p-type conduction, we report a completely catalyst-free, selective area molecular beam epitaxial growth that establishes n-type behavior under Si doping. The vapor–solid selective area growth on prepatterned Si (111) substrates is enabled by an important in situ substrate pretreatment to create an As-terminated 1 × 1-Si(111) substrate necessary for the growth of [111]-oriented GaAs:Si NWs with a large aspect ratio and high yield. Correlated resonant Raman scattering and single-NW micro-photoluminescence (μPL) experiments confirm the n-type nature of the Si-doped GaAs NWs evidenced by a dominant SiGa local vibrational Raman mode, a distinct band filling effect (up to > 10 meV) along with increased PL peak broadening upon increased Si concentration. Excessive Si doping is further found to induce some auto-compensation evidenced by red-shifted PL and the appearance of minor SiAs and SiGa–SiAs pair-like local vibrational Raman modes. Employing excitation power dependent μPL, we further discern signatures in below-gap defect luminescence (∼1.3–1.45 eV) arising from structural defects and Si dopant-point defect complexes.The realization of n-type conduction in directly bottom-up grown Si-doped GaAs nanowires (NWs) by molecular beam epitaxy has remained a long-standing challenge. Unlike the commonly employed vapor–liquid−solid growth, where the amphoteric nature of Si dopants induces p-type conduction, we report a completely catalyst-free, selective area molecular beam epitaxial growth that establishes n-type behavior under Si doping. The vapor–solid selective area growth on prepatterned Si (111) substrates is enabled by an important in situ substrate pretreatment to create an As-terminated 1 × 1-Si(111) substrate necessary for the growth of [111]-oriented GaAs:Si NWs with a large aspect ratio and high yield. Correlated resonant Raman scattering and single-NW micro-photoluminescence (μPL) experiments confirm the n-type nature of the Si-doped GaAs NWs evidenced by a dominant SiGa local vibrational Raman mode, a distinct band filling effect (up to > 10 meV) along with increased PL peak broadening upon increased Si concentrat...

中文翻译：

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通过分子束外延生长的无催化剂 Si 掺杂 GaAs 纳米线的 n 型行为演示

通过分子束外延在直接自底向上生长的 Si 掺杂 GaAs 纳米线 (NW) 中实现 n 型传导仍然是一个长期存在的挑战。与常用的汽-液-固生长不同，Si 掺杂剂的两性性质诱导 p 型传导，我们报告了一种完全无催化剂、选择性区域分子束外延生长，在 Si 掺杂下建立 n 型行为。在预制图案的 Si (111) 衬底上进行气固选择性区域生长是通过重要的原位衬底预处理来实现的，以创建 [111] 取向 GaAs 生长所需的 As 端基 1 × 1-Si(111) 衬底：具有大纵横比和高产率的 Si NW。相关的共振拉曼散射和单 NW 微光致发光 (μPL) 实验证实了 Si 掺杂的 GaAs NW 的 n 型性质，这证明了主导的 SiGa 局部振动拉曼模式，独特的带填充效应（高达 > 10 meV）随着Si浓度增加，PL峰展宽增加。进一步发现过度的 Si 掺杂会引起一些自动补偿，这可以通过红移 PL 和少量 SiAs 和 SiGa-SiAs 对状局部振动拉曼模式的出现来证明。使用依赖于激发功率的 μPL，我们进一步辨别了由结构缺陷和 Si 掺杂点缺陷复合物引起的低于间隙缺陷发光（~1.3-1.45 eV）的特征。通过分子束外延在直接自底向上生长的 Si 掺杂 GaAs 纳米线 (NW) 中实现 n 型传导仍然是一个长期存在的挑战。与常用的汽-液-固生长不同，Si 掺杂剂的两性性质诱导 p 型传导，我们报告了一种完全无催化剂、选择性区域分子束外延生长，在 Si 掺杂下建立 n 型行为。在预制图案的 Si (111) 衬底上进行气固选择性区域生长是通过重要的原位衬底预处理来实现的，以创建 [111] 取向 GaAs 生长所需的 As 端基 1 × 1-Si(111) 衬底：具有大纵横比和高产率的 Si NW。