室温工作的氮化物量子点单光子源机理研究

Single photon emitters hold the promise to serve as quantum bits in quantum communication, linear optical quantum computing and cryptography. Quantum dot single photon emitters have been recognized as one of the promising approach for deterministic squeezed light source and solid-state quantum computer system. Due to their thermal and chemical stability, wide wavelength tunability from the ultraviolet to the near-infrared spectral range, especially large exciton binding energy, III-nitrides quantum dots (QDs) are the most promising candidates for single photon emitting devices which is able to operate at room temperature. This proposal will focus on the growth of GaN atomic layer quantum well structures (ALQWS) by molecular beam epitaxy (MBE), explore the dynamic growth physics, and discover the fine band structure and residual strain state of GaN atomic layer structures with extremely strong confinement. Subsequently, the GaN/AlGaN ALQWS will be fabricated into periodically arranged nanowire arrays with identically shape by the top-down approach, i.e. a GaN/AlGaN quantum dot embedded in a single nanowire, which yields a three-dimensional charge carrier confinement, enabling ultraviolet single photon emission at room temperature. We then will deeply study the radiative recombination mechanisms of confined excitons, emission properties as a function of frequency and temperature, and find a way to improve of single photon emission efficiency.

单光子发射是量子通讯中量子比特传输、量子线性光学计算和量子密码学的重要组成部分。量子点单光子源被公认是实现确定性量子光源和固态体系量子计算机最有前途的方向之一。III族氮化物量子点不但具有很好的热稳定性和抗化学腐蚀能力、发光波长从深紫外到近红外波段宽幅度可调，而且具有较大的激子束缚能，可以实现单光子源的室温工作。本项目将利用分子束外延（MBE）技术生长GaN原子层量子阱结构，研究其外延生长动力学，研究强受限GaN/AlGaN原子层量子阱结构的精细能带结构和应变状态；采用自上而下的微纳加工技术路线将GaN/AlGaN原子层量子阱结构制备成周期性排列的具有规则形状的阵列纳米线，形成耦合GaN/AlGaN量子点的纳米线阵列结构，实现优异的三维限制，进而制备出基于强受限GaN量子点的室温工作紫外单光子源，深入研究单光子源的辐射复合机理、频率依赖关系、温度特性和单光子发射效率的提升机制。

量子点单光子源被公认是实现确定性量子光源和固态体系量子计算机最有前途的方向之一。III族氮化物量子点不但具有很好的热稳定性和抗化学腐蚀能力、发光波长从深紫外到近红外波段宽幅度可调，而且具有较大的激子束缚能，可以实现单光子源的室温工作。本项目利用分子束外延（MBE）技术深入研究了GaN/AlGaN原子层结构的外延生长动力学，揭示了GaN原子层外延生长规律，实现了高质量、强受限GaN原子层量子阱结构的可控生长。采用了“自上而下”的微纳加工技术将GaN/AlGaN原子层量子阱结构制备成周期性排列的具有规则形状的阵列纳米线，形成耦合GaN/AlGaN量子点的纳米线阵列结构，实现优异的三维限制，纳米线直径55 nm，进而制备出基于强受限GaN量子点的单光子源结构。同时利用“自下而上”的自组装技术制备了GaN/AlN量子点耦合纳米线结构，并利用STEM-CL获得了耦合量子点发光性质在时间、空间的上的超高分辨表征，16 K下量子点发光峰在287 nm附近，半峰宽小于18 meV。基于传统自组装纳米线生长工艺，我们创新性地提出利用热分解+再生长的方式来实现强受限InGaN/GaN量子点耦合纳米线结构，并通过HBT二阶相关度测试验证了其单光子发射特性，获得低温下发射光子的二阶相关度g2(0)因子为0.061±0.04；采用了GaN点缺陷来实现室温单光子发射，实现室温近红外波段的单光子发射，波长在750 nm附近，HBT测试表明实现了室温下的反聚束效应，扣除本底前二阶相关度g2(0)因子为0.39；通过本项目的实施为III族氮化物量子点单光子源的实用化奠定基础。