Kort Kenneth R, Hung P Y, Loh Wei-Yip, Bersuker Gennadi, Banerjee Sarbajit
Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260 USA.
Appl Spectrosc. 2015;69(2):239-42. doi: 10.1366/14-07602. Epub 2015 Jan 1.
The advent and exponential growth of mobile computing has spurred greater emphasis on the adoption of III-V compound semiconductors in device architectures. The introduction of high charge carrier densities within InxGa1-xAs and the development of metrologies to quantitate the extent of doping have thus emerged as an urgent imperative. As an amphoteric dopant, Si begins to occupy anionic sites at high concentrations, thereby limiting the maximum carrier density that can be obtained upon Si doping of III-V semiconductors. Here, we present Raman results on sequentially doped In0.53Ga0.47As wherein sulfur monolayer doping is used to introduce additional carrier density to Si-doped samples. The sequential doping of Si and S allows for high carrier concentrations of up to 1.3 × 10(19) cm(-3) to be achieved without damaging the III-V lattice. The coupling of the plasmon in the doped samples to the longitudinal optic phonons allows Raman spectroscopy to serve as an excellent probe of the extent of dopant activation, charge carrier density, and the surface depletion region. In particular, the energy position of a high-frequency coupled mode (HFCM) that is detected above 400 cm(-1) is used to extract the free electron density in these samples. The extracted free electron densities are well correlated with measured sheet resistance values and the carrier densities deduced from Hall measurements.
移动计算的出现及其指数级增长促使人们更加重视在器件架构中采用III-V族化合物半导体。因此，在InxGa1-xAs中引入高电荷载流子密度以及开发用于定量掺杂程度的计量学方法已成为当务之急。作为一种两性掺杂剂，硅在高浓度时开始占据阴离子位点，从而限制了III-V族半导体进行硅掺杂时可获得的最大载流子密度。在此，我们展示了对顺序掺杂的In0.53Ga0.47As的拉曼结果，其中硫单层掺杂用于向硅掺杂样品中引入额外的载流子密度。硅和硫的顺序掺杂能够在不破坏III-V族晶格的情况下实现高达1.3×10(19) cm(-3)的高载流子浓度。掺杂样品中的等离激元与纵向光学声子的耦合使得拉曼光谱能够成为掺杂剂激活程度、电荷载流子密度和表面耗尽区的出色探测手段。特别是，在400 cm(-1)以上检测到的高频耦合模式（HFCM）的能量位置被用于提取这些样品中的自由电子密度。提取的自由电子密度与测量的薄层电阻值以及从霍尔测量推导的载流子密度具有良好的相关性。
