论文标题
在低温下光致发光证明了散装黑磷的激子
Excitons in bulk black phosphorus evidenced by photoluminescence at low temperature
论文作者
论文摘要
黑色磷（BP）的原子层呈现出独特的光电特性，该特性由直接可调的带隙在广泛的光谱范围内占主导地位，从可见光到中红外。在这项工作中，我们研究了BP单晶在非常低温下的红外光致发光。在2 K处观察到接近边的重组，包括0.276 eV时的主要激光转变，在0.278 eV时较弱。通过各向异性Wannier-mott模型计算自由性外激体结合能，发现等于9.1 MeV。相反，在高温下发现0.276 eV峰的PL强度淬火率较小，这是由于在浅杂质上的自由激子的定位。该分析使我们分别将0.276 eV和0.278 eV线归因于BP中的绑定激子和免费激子。结果，在2K时，将大量BP带隙的值精制到0.287 eV。
Atomic layers of Black Phosphorus (BP) present unique opto-electronic properties dominated by a direct tunable bandgap in a wide spectral range from visible to mid-infrared. In this work, we investigate the infrared photoluminescence of BP single crystals at very low temperature. Near-bandedge recombinations are observed at 2 K, including dominant excitonic transitions at 0.276 eV and a weaker one at 0.278 eV. The free-exciton binding energy is calculated with an anisotropic Wannier-Mott model and found equal to 9.1 meV. On the contrary, the PL intensity quenching of the 0.276 eV peak at high temperature is found with a much smaller activation energy, attributed to the localization of free excitons on a shallow impurity. This analysis leads us to attribute respectively the 0.276 eV and 0.278 eV PL lines to bound excitons and free excitons in BP. As a result, the value of bulk BP bandgap is refined to 0.287 eV at 2K.
