Single-photon defect emitters (SPEs), especially those with magnetically and optically addressable spin states, in technologically mature wide bandgap semiconductors are attractive for realizing integrated platforms for quantum applications. Broadening of the zero phonon line (ZPL) caused by dephasing in solid state SPEs limits the indistinguishability of the emitted photons. Dephasing also limits the use of defect states in quantum information processing, sensing, and metrology. In most defect emitters, such as those in SiC and diamond, interaction with low-energy acoustic phonons determines the temperature dependence of the dephasing rate and the resulting broadening of the ZPL with the temperature obeys a power law. GaN hosts bright and stable single-photon emitters in the 600–700 nm wavelength range with strong ZPLs even at room temperature. In this work, we study the temperature dependence of the ZPL spectra of GaN SPEs integrated with solid immersion lenses with the goal of understanding the relevant dephasing mechanisms. At temperatures below ~ 50 K, the ZPL lineshape is found to be Gaussian and the ZPL linewidth is temperature independent and dominated by spectral diffusion. Above ~ 50 K, the linewidth increases monotonically with the temperature and the lineshape evolves into a Lorentzian. Quite remarkably, the temperature dependence of the linewidth does not follow a power law. We propose a model in which dephasing caused by absorption/emission of optical phonons in an elastic Raman process determines the temperature dependence of the lineshape and the linewidth. Our model explains the temperature dependence of the ZPL linewidth and lineshape in the entire 10–270 K temperature range explored in this work. The ~ 19 meV optical phonon energy extracted by fitting the model to the data matches remarkably well the ~ 18 meV zone center energy of the lowest optical phonon band (\(E_{2}(low)\)) in GaN. Our work sheds light on the mechanisms responsible for linewidth broadening in GaN SPEs. Since a low energy optical phonon band (\(E_{2}(low)\)) is a feature of most group III–V nitrides with a wurtzite crystal structure, including hBN and AlN, we expect our proposed mechanism to play an important role in defect emitters in these materials as well.

技术成熟的宽带隙半导体中的单光子缺陷发射器 (SPE)，尤其是那些具有磁性和光学可寻址自旋态的发射器，对于实现量子应用的集成平台具有吸引力。由固态 SPE 中的相移引起的零声子线 (ZPL) 的展宽限制了发射光子的不可区分性。去相位还限制了缺陷态在量子信息处理、传感和计量学中的使用。在大多数缺陷发射器中，例如 SiC 和金刚石中的缺陷发射器，与低能声学声子的相互作用决定了相移率的温度依赖性，并且由此产生的 ZPL 随温度的展宽遵循幂律。GaN 在 600–700 nm 波长范围内拥有明亮且稳定的单光子发射器，即使在室温下也具有强 ZPL。在这项工作中，我们研究了与固体浸没透镜集成的 GaN SPE 的 ZPL 光谱的温度依赖性，目的是了解相关的相移机制。在低于 ~ 50 K 的温度下，发现 ZPL 线形呈高斯分布，并且 ZPL 线宽与温度无关并受光谱扩散支配。高于 ~ 50 K，线宽随温度单调增加，线形演变为洛伦兹线形。非常值得注意的是，线宽的温度依赖性不遵循幂律。我们提出了一个模型，其中由弹性拉曼过程中光学声子的吸收/发射引起的相移决定了线形和线宽的温度依赖性。我们的模型解释了 ZPL 线宽和线形在本工作探索的整个 10–270 K 温度范围内的温度依赖性。通过将模型拟合到数据中提取的~ 19 meV 光学声子能量与最低光学声子带的~ 18 meV 区域中心能量非常匹配（\(E_{2}(low)\) ) 在 GaN 中。我们的工作阐明了 GaN SPE 中线宽展宽的机制。由于低能量光学声子带 ( \(E_{2}(low)\) ) 是大多数具有纤锌矿晶体结构的 III-V 族氮化物的特征，包括 hBN 和 AlN，我们希望我们提出的机制发挥重要作用在这些材料中的缺陷发射体中也有作用。