寬能隙半導體微共振腔元件之研究

Abstract

本計劃目的在於使用寬能隙半導體材料如氮化鎵或氧化鋅製作微共振腔元件以探討光 與物質間的強耦合作用以及微共振腔中極化子之特性並製作出實用化的新型量子光電 元件。微共振腔極化子是一種半光半物質(激子)的一種準粒子，其波色子的特性以及利 用最終態散射將可以在中達到單一態的動態玻色-愛因斯坦凝聚，而由於寬能隙半導體 材料通常具有較大的激子束縛能以及振子強度，因此本計畫將會利用微共振腔極化子 的玻色子特性在氧化鋅微共振腔中達到室溫操作的玻色-愛因斯坦凝聚態，此種玻色- 愛因斯坦凝聚態可以實現一種極低臨界能量密度的新型極化子雷射，為一種不需要達 到居量反轉即可產生同調光的低功耗光電元件。我們也利用共振激發的機制將氧化鋅 微共振腔元件操作在特定之極化子散射的條件下，利用極化子之受激散射達成室溫操 作並具有極低閾值條件之微光參量振盪器元件。本計畫也將氮化鎵微共振腔元件製作 成電激發的極化子發光二極體，利用快速的拉比振盪改善發光二極體非輻射再結合所 引起的內部量子效率低落的問題，以邁向實用化極化子元件之目標。

The main purpose of this project is to use wide-bandgap materials such as ZnO and GaN to observe the strong light-matter coupling interaction and microcavity polariton behavior and to develop practical and novel quantum optoelectronics. Microcavity polariton composing of photon and exciton is a half-light/half matter quasi-particle. The bosonic characteristics can achieve the dynamic Bose-Einstein condensation in the microcavity device through the final state scattering. On the other hand, the large exciton binding energy and oscillator strength of wide bandgap materials could allow the Bose-Einstein condensation operating at the room temperature. Within the three years, we plan to achieve room temperature dynamic Bose-Einstein condensation and an ultralow-threshold polariton laser in the ZnO-based microcavity. Polariton laser is a low threshold coherent light source which doesn’t require population inversion. We also plan to operate the ZnO-based microcavity at stimulated scattering regime by using resonant pumping technique to demonstrate a room temperature micro-OPO with ultra-low threshold compared to traditional χ(2) nonlinear optical material-based OPO. Toward a practical polariton device, this project would use GaN to realize a high efficiency current injection polariton GaN LED operated at room temperature since fast Rabi oscillation in the strong coupling regime could efficiently suppress the non-radiative recombination thus to enhance the internal quantum efficiency. In addition, the significantly lower density of states of polaritons makes extra low-threshold current injection polariton lasers possible as compared to conventional semiconductor lasers based on GaN materials