Si and N - Vacancy color centers in discrete diamond nanoparticles: Raman and fluorescence spectroscopic studies

Abstract

The present study reports on an innovative method to prepare discrete diamond nanoparticles or nanodiamonds (NDs) with high structural and optical quality through top-down approach by controlled oxidation of pre-synthesized nanocrystalline diamond (NCD) film. These NDs are studied for their structural and optical properties using atomic force microscopy (AFM), Raman and fluorescence (FL) spectroscopy. While AFM analysis confirms uniform distribution of discrete NDs with different sizes varying from a few tens of nanometers to about a micron, spectroscopic investigations reveal the presence of impurity -vacancy related color centers exhibiting FL at 637 and 738 nm as a function of particle size. In addition, an intense emission originating from vacancy centers associated with N and Si (SiVˉ) is observed for all NDs at the temperature close to liquid nitrogen. A detailed spectral analysis is carried out on the structural defects in these NDs. The full width at half maximum of diamond Raman band ( ~ 1332 cm -1 ) is found to be as narrow as 1.5 cm -1 which reveals the superior structural quality of these NDs.Further, mapping of diamond Raman and FL spectra of SiVˉ confirm the uniform distribution of NDs throughout the substrate. The narrow line widths and a minimal shift in peak positions of Raman and FL spectra endorse this aspect.

Studies on tuning surface electronic properties of hydrogenated diamond by oxygen functionalization

“…Microcrystalline diamond films were grown on SiO2/Si by hot filament chemical vapor deposition using methane and hydrogen as feedstocks in the ratio of 2 : 200, as discussed earlier [19,20]. Subsequent to growth, the in-situ hydrogen termination on diamond surface was achieved by admitting ultrahigh pure hydrogen into the chamber at a flow rate of 200 sccm for 1200 s under working pressure of ~ 40 mbar.…”

Structural, Raman and photoluminescence studies on nanocrystalline diamond films: Effects of ammonia in feedstock

“…Figure 4a shows the room temperature PL spectra of the diamond films grown at different N/C ratio in feedstock by an excitation wavelength of 532 nm. The undoped diamond film N0 displays two broad PL bands near 630 and 700 nm which are typical for NCD structure [32]. The PL intensity enhances significantly in the studied wavelength range at a small amount of N doping ( N/C ratio = 0.13) in diamond lattice and also the maximum peak is shifted from about 630 nm to 700 nm.…”

“…Nitrogen doped diamond films were grown by a custom designed HFCVD system and the details could be found elsewhere [31,32]. The diamond films are grown on Si (111) and the substrates were chemo-mechanically polished with micron level diamond paste prior to growth.…”

Reducing Threading Dislocations of Single-Crystal Diamond via In Situ Tungsten Incorporation

“…Defects in diamond include point defects [9], stacking faults (SFs) [10], and threading dislocations (TDs) [11]. Point defects are mainly contained in nitrogen-vacancy centers (NV 0 , NV − ) [12], silicon vacancy centers (SiV − ) [13], and hydrogen-related defects [14]. Owing to mechanical damage, SFs usually start from the substrate and then penetrate through the growth layer [15].…”