Centre for Nanoscience and Nanotechnology, CNRS, University Paris-Sud/Paris-Saclay , 91460 Marcoussis, France.
Institut Photovoltaïque d'Ile-de-France (IPVF) , 92160 Antony, France.
Nano Lett. 2017 Nov 8;17(11):6667-6675. doi: 10.1021/acs.nanolett.7b02620. Epub 2017 Oct 23.
We present an effective method of determining the doping level in n-type III-V semiconductors at the nanoscale. Low-temperature and room-temperature cathodoluminescence (CL) measurements are carried out on single Si-doped GaAs nanowires. The spectral shift to higher energy (Burstein-Moss shift) and the broadening of luminescence spectra are signatures of increased electron densities. They are compared to the CL spectra of calibrated Si-doped GaAs layers, whose doping levels are determined by Hall measurements. We apply the generalized Planck's law to fit the whole spectra, taking into account the electron occupation in the conduction band, the bandgap narrowing, and band tails. The electron Fermi levels are used to determine the free electron concentrations, and we infer nanowire doping of 6 × 10 to 1 × 10 cm. These results show that cathodoluminescence provides a robust way to probe carrier concentrations in semiconductors with the possibility of mapping spatial inhomogeneities at the nanoscale.
我们提出了一种在纳米尺度上测定 n 型 III-V 半导体掺杂水平的有效方法。对单掺硅的 GaAs 纳米线进行了低温和室温下的阴极荧光（CL）测量。光谱向高能（Burstein-Moss 位移）的移动和发光光谱的展宽是电子密度增加的特征。将它们与经过校准的 Si 掺杂 GaAs 层的 CL 光谱进行比较，这些 Si 掺杂 GaAs 层的掺杂水平是通过 Hall 测量确定的。我们应用广义普朗克定律来拟合整个光谱，同时考虑到导带中的电子占据、能带缩窄和能带尾部。电子费米能级用于确定自由电子浓度，我们推断出纳米线的掺杂浓度为 6×10 到 1×10 cm。这些结果表明，阴极荧光提供了一种在半导体中探测载流子浓度的可靠方法，有可能在纳米尺度上探测空间不均匀性。
