The bottom-up synthesis process often allows the growth of metastable phase nanowires instead of the thermodynamically stable phase. Herein, we synthesized Cd₃As₂ nanowires with a controlled three-dimensional Dirac semimetal phase using a chemical vapor transport method. Three different phases such as the body centered tetragonal (bct), and two metastable primitive tetragonal (P4₂/nbc and P4₂/nmc) phases were identified. The conversion between three phases (bct → P4₂/nbc → P4₂/nmc) was achieved by increasing the growth temperature. The growth direction is [110] for bct and P4₂/nbc and [100] for P4₂/nmc, corresponding to the same crystallographic axis. Field effect transistors and photodetector devices showed the nearly same electrical and photoelectrical properties for three phases. Differential conductance measurement confirms excellent electron mobility (2 × 10⁴ cm²/(V s) at 10 K). Negative photoconductance was first observed, and the photoresponsivity reached 3 × 10⁴ A/W, which is ascribed to the surface defects acting as trap sites for the photogenerated electrons.

中文翻译：

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Cd3As2纳米线的相控生长及其负光电导性。

自下而上的合成过程通常允许亚稳态相纳米线的生长，而不是热力学稳定相的生长。在这里，我们使用化学气相传输方法合成了具有受控三维Dirac半金属相的Cd ₃ As ₂纳米线。确定了三个不同的相，例如体心四方相（bct）和两个亚稳原始四方相（P 4 ₂ / nbc和P 4 ₂ / nmc）相。三相之间的转换（bct→ P 4 ₂ / nbc → P 4 ₂ / nmc）是通过提高生长温度来实现的。bct和P 4 ₂ / nbc的生长方向为[1 1 0]，P 4 ₂ / nmc的生长方向为[ 100] ，对应于相同的结晶轴。场效应晶体管和光电检测器器件在三相中显示出几乎相同的电和光电特性。差分电导测量结果证实了优异的电子迁移率（在10 K下为2×10 ⁴ cm ² /（V s））。首先观察到负电导，光响应达到3×10 ⁴ A / W，归因于表面缺陷，充当光生电子的俘获位点。