- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Enhanced and switchable silicon-vacancy photoluminescence in air-annealed nanocrystalline diamond films
摘要： Silicon vacancy (SiV) centers in CVD-deposited nanodiamond particles or films always exhibit a photoluminescent (PL)-quenching behavior. Herein, in order to overcome this issue, air annealing of nanocrystalline diamond (NCD) films with uniform doping of Si atoms is employed to improve the PL emission efficiency of SiV centers. Without severe mass loss in diamond, SiV centers exhibit an increased PL emission intensity at 738 nm with an increased annealing temperature and time. In comparison to the untreated film, the maximum PL enhancement reaches about 200 and 1473 folds when the NCD films are annealed at 600 oC for 60 min and 700 oC for 20 min, respectively. Such giant increase in SiV PL emission is mainly attributed to the transition of diamond surface from hydrogen to oxygen termination together with the optimized crystalline quality of the annealed films, as confirmed by the HRTEM, Raman and XPS measurements. A schematic model based on the theory of surface band bending is proposed to elucidate the mechanism of the SiV PL enhancement in oxygen-terminated NCD films: a near-surface light trap layer formed in hydrogen-terminated NCD is converted during the oxidation process, leading to the additional collection of SiV PL emission from the inner layer.
关键词： thermal treatment,luminescence,surface modification,color center,nano-crystalline diamond
更新于2025-09-12 10:27:22
-
Microwave cavity perturbation of nitrogen doped nano-crystalline diamond films
摘要： Non-contact and non-destructive electrical conductivity measurements of nitrogen doped nano-crystalline diamond films have been demonstrated using a microwave cavity perturbation system. The conductivity of the films was controlled by simply varying the CH4 gas concentration during microwave plasma assisted chemical vapour deposition, thereby promoting the formation of sp2 carbon at the grain boundaries. The presence of sp2 carbon is verified through Raman spectroscopy, x-ray photoelectron spectroscopy and electron energy loss spectroscopy, while scanning electron microscopy confirms an increasing surface area for sp2 to form. The microwave cavity perturbation results show that the measured cavity quality factor varies with CH4 concentration. The extraction of conductivity is achieved through a depolarisation model, which must be considered when the sample is smaller than the cavity and through both electric and magnetic field perturbations. The microwave measurements are comparable to contacting and damaging measurements when the film conductivity is greater than the substrate, thus demonstrating an invaluable method for determining conductivity without the need for depositing any electrodes on the film.
关键词： non-contact,microwave dielectric spectroscopy,nano-crystalline diamond,electrical conductivity
更新于2025-09-04 15:30:14