Controlling electronic states of GaN quantum dots by external electric field and its application to the spectroscopy

本研究的目的是了解并通过外电场控制具有强内建电场的GaN量子点中的电子态。我们开发了具有单点光谱和外加电场能力的光学和电学实验装置。我们首次在自组装GaN量子点中观察到作为氮化物材料系统的精细结构分裂。我们还成功地观察到了嵌入在AlGaN/GaN纳米线中的GaN量子点的精细结构分裂，并发现在激子发射能量为4.2 eV时，双激子结合能高达52 meV。细结构分裂能和双激结合能都是反映量子点内电子与空穴相互作用的重要物理量。

The objective in this study is the understanding and the controlling via external electric field of electronic states in a GaN quantum dot with strong built-in electric field. We have developed the optical and electrical experimental setup with the capability to perform both single dot spectroscopy and applying electric field. We have observed fine-structure splitting in a self-assembled GaN quantum dot for the first time as a nitride material system. We have also successfully observed the fine-structure splitting in a GaN quantum dot embedded in AlGaN/GaN nanowires, and have found that the biexciton binding energy reaches as large as 52 meV at the exciton emission energy of 4.2 eV. Both the fine-structre splitting and biexction binding energy are the significant physical quantities reflecting the interaction between electrons and holes confined in a quantum dot.