太赫兹辐射场下的石墨烯光生载流子和光子发射

Photon-excited carriers and emission of graphene in terahertz radiation fields

通过半经典的玻尔兹曼平衡方程理论研究了太赫兹辐射场下的石墨烯光生载流子和光子发射.研究得到了太赫兹辐射场下石墨烯的光生载流子浓度和光子发生率的解析公式.研究发现,掺杂电子浓度越小,或者温度越低,光生载流子浓度越大;掺杂电子浓度越大,或者温度越低,石墨烯的光子发射率越大.通过改变门电压或温度,可以有效地调控石墨烯光生载流子浓度和光子发射概率.理论研究结果和解析表达式对发展以石墨烯为基础的新型太赫兹光电器件具有重要的参考价值.

Graphene exhibits excellent electronic and optical properties, which has been proposed as an advanced material for new generation of electronic and optical devices. We develop a detailed theoretical mode to investigate the optical properties of graphene-wafer systems. The photon-excited carriers and emission are obtained based on the mass-balance equation and the charge number conservation equation, which are derived from Boltzmann equation. The analytical results of photon excited carrier density and photon emission coefficient are achieved self-consistently in terahertz radiation fields. It is found that the photon excited carrier density increases with doped electron density or temperature decreasing. The higher the doped electron density and the lower the temperature, the larger the photon emission coefficient is. The optical emission increases with doped electron density increasing, and the optical emission increases with temperature decreasing. It shows that photon-excited carriers and emission of graphene can be effectively tuned by gate voltage. These theoretical results can be used to understand the relevant experimental findings. This theoretical study can benefit the applications in advanced optoelectronic devices based on graphene, especially terahertz devices.