Raman and PL spectra from Narrowband photoluminescence of Tin-Vacancy colour centres in Sn-doped chemical vapour deposition diamond microcrystals

Tin-Vacancy (Sn-V) colour centres in diamond have a spin coherence time in the millisecond range at temperatures of 2 K, so they are promising to be used in diamond-based quantum optical devices. However, the incorporation of large Sn atoms into a dense diamond lattice is a non-trivial problem. The objective of our work is to use microwave plasma-assisted chemical vapour deposition (CVD) to grow Sn-doped diamond with submicron SnO2 particles as a solid-state source of impurity. Well-faceted diamond microcrystals with sizes of a few micrometres were formed on AlN substrates. The photoluminescence (PL) signal with zero-phonon line (ZPL) peak for Sn-V centre at ≈620 nm was measured at room temperature (RT) and at 7 K. The peak width (full width at half-maximum) was measured to be 1.1–1.7 nm at RT and ≈0.05 nm at 7 K. The observed variations of ZPL shape and position, in particular, narrowing of PL peak at RT and formation of single-line fine structure at low-T, are attributed to strain in the crystallites. The diamond doping with Sn via CVD process offers a new route to from Sn-V colour centre in the bulk of the diamond crystallites.This article is part of the Theo Murphy meeting issue 'Diamond for quantum applications'.

金刚石中的锡空位（Sn-V）色心在2开尔文温度下的自旋相干时间可达毫秒量级，因此其在金刚石基量子光学器件中具备良好的应用潜力。然而，将大尺寸锡原子掺入致密的金刚石晶格是一项颇具挑战性的难题。本研究采用微波等离子体辅助化学气相沉积（CVD）技术，以亚微米级二氧化锡（SnO₂）颗粒作为固态杂质源，生长掺锡金刚石。最终在氮化铝（AlN）衬底上制备出尺寸为数微米、形貌规整的金刚石微晶。实验分别在室温（RT）与7开尔文温度下，测得对应Sn-V色心、中心波长约620纳米的光致发光（PL）零声子线（ZPL）信号。室温下该峰的半高全宽为1.1~1.7纳米，7开尔文下则约为0.05纳米。观测到的零声子线形状与位置变化，尤其是室温下光致发光峰的窄化以及低温下单线条精细结构的形成，均可归因于微晶内部的晶格应力。通过化学气相沉积工艺实现锡掺杂金刚石，为在金刚石微晶体相中制备Sn-V色心提供了全新的技术路径。本文属于《西奥·墨菲专题集：面向量子应用的金刚石》特刊内容。