报告时间: 2023年11月2日 下午14:00(14:00,Nov. 2, 2023)

报告地点: 物质科研楼A309会议室 (Room A309, Material Science Building)

报告题目：Nitrogen and silicon defects in co-doped CVD diamond and their charge state behavior

报告人：吴旭旭 博士

报告摘要：Both the neutrally- and negatively-charged silicon vacancy (SiV0/– ) centers in diamond have great potential for quantum information applications due to their highly coherent optical emission, and long spin coherence lifetimes at 4 K and < 100 mK1 , respectively. The recent realization of optically detected magnetic resonance (ODMR) and coherent control of neutral silicon vacancy centers (SiV0 ) via bound exciton states lays the foundations for a highly-exploitable quantum technology resource 2 . However, the electronic structure of SiV0 and its charge-state dynamics are not completely understood 3 . In order to realize applications of silicon vacancy centers in either charge state, it is vital to figure out the mechanism of charge transfer in silicon vacancies, in order either to stabilize ensembles of SiV– for ensemble quantum memory applications 4 , or to stabilize SiV0 for quantum repeater applications. In either situation, charge instability is disadvantageous for engineering applications, resulting in coherence loss and fluorescence blinking. Nevertheless, deliberate photoionization of SiV0/– is potentially useful in photocurrent detection of magnetic resonance (PDMR) 5,6 , mirroring such work on NV– , but requires an intimate understanding of charge behavior to be exploitable.

Our work aims to study the charge state dynamics of ensemble defects in diamond via studying highly nitrogen and silicon doped CVD diamonds. The annealing treatment of silicon and nitrogen contained CVD synthetic diamonds with temperatures in the range of 1600℃ to 2400℃ reveals the behaviors of silicon and nitrogen incorporation by tracking critical defects. A set of EPR multiple lines with S=1/2 at approximately g = 2.004 is identified to be a new defect SiVN0 , which is annealed in above 2000℃. Besides, since the co-doping naturally leads to multiple defects that possess numerous close energy levels, charge transfer in this type of sample is significant. The static charge transfer and charge dynamics are observed in various defects. driven by bandgap UV irradiation and heating treatment (550℃) in ambient. Moreover, the significance of photochromism caused by the charge transfer of SiV between its optical active charge states and inactive one leads to experimentally proving the existence of SiV2- that is EPR silent and has no optical features observed to date. Additionally, previous reports predicting an anomalous luminescence centre with ZPL at 499 nm found in annealed CVD synthetic diamond related to the SixNyV complexes are excluded by this work. A set of unknown EPR lines centred around g = 2.003 is found in ultra-low nitrogen CVD diamonds with 499 nm long-lifetime luminescence center indicating an unknown defect.

报告人简介：吴旭旭 英国华威大学 博士研究生即将毕业 研究方向：钻石色心表征，新型钻石缺陷研究。