Studies of defects and impurities in diamond thin films

Journal of Coating Science and Technology, 2015

Microcrystalline diamond films doped with silicon have been grown on aluminum nitride substrates by a microwave plasma CVD. The doping has been performed via adding silane in various concentrations to CH4-H2 reaction gas mixture in course of the deposition process. The films produced at the substrate temperatures of 750 to 950°C have been characterized by SEM, AFM, Raman and photoluminescence (PL) spectroscopy to assess the effect of Si doping on the diamond structure. The doped films showed bright photoluminescence of silicon-vacancy (SiV) color centers at 738 nm wavelength as well as noticeable side band at 723 nm. The optimum doping condition (SiH4/CH4 0.6%), that maximize the SiV PL emission, was determined for the range of silane concentrations SiH4/CH4 (0.0-0.9%) explored. A further PL enhancement can be achieved by increase in the substrate temperature. The applied in situ doping from gas phase is shown to be an easy and effective method to incorporate Si in diamond in a controllable way.

Diamond and Related Materials, 1993

Diamond films were deposited by microwave-assisted chemical vapour deposition on silicon substrates using methane as a hydrocarbon precursor. The films were investigated by scanning electron spectroscopy, Raman spectroscopy, electron spin resonance (ESR) and X-ray diffraction. With increasing methane concentration, the diamond crystallites underwent morphological changes which were accompanied by important changes in the Raman diamond line and the ESR signal. Increasing width and decreasing intensity of the Raman diamond line were observed to correlate with increasing spin densities and decreasing grain size.

Physica Status Solidi (a), 2006

Nanocrystalline diamond (NCD) films were grown by microwave plasma CVD in hydrogen-based gas mixture. Deposition experiments were performed at different temperatures varying from 370 to 1100 °C. Before growth step, silicon (100) oriented substrates were nucleated by bias enhanced nucleation procedure and glass substrates were pretreated in ultrasonic bath. Optical, structural and morphological properties of NCD films were systematically studied by using an optical spectroscopy, scanning electron microscopy and Raman spectroscopy. NCD films were optically transparent in wide range and had high refractive index of 2.34. All deposited samples exhibited diamond characteristic line in the Raman spectrum. The growth kinetic was attributed to the hydrogen abstraction model. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

(2012) Bulletin of Materials Science, 35 (1), pp. 1-5.

Preliminary results of growth of thin diamond film in a recently installed 3 kW capacity microwave plasma activated CVD (MW-PACVD) system are being reported. The films were deposited on Si (100) substrate at 850°C using methane and hydrogen mixture at 1·5 kW MW power. The grown polycrystalline films were characterized by micro-Raman, transmission electron microscope (TEM), spectrophotometer and atomic force microscope (AFM). The results were compared with that of a thicker diamond film grown elsewhere in a same make MWPACVD system at relatively higher power densities. The presence of a sharp Raman peak at 1332 cm -1 confirmed the growth of diamond, and transmission spectra showed typical diamond film characteristics in both the samples. Typical twin bands and also a quintuplet twinned crystal were observed in TEM, further it was found that the twinned region in thin sample composed of very fine platelet like structure.

Diamond and Related Materials, 1993

Diamond films have been deposited in a spherical (diameter 400 mm) ultrahigh vacuum chamber (base pressure less than 10-8 mbar) by microwave plasma decomposition of hydrogen-methane gas mixtures. A separately pumped loadlock prevents nitrogen contamination of the growth chamber when substrates up to 100 mm in diameter enter or leave. During deposition the plasma ball sits above the substrate and is remote from the chamber walls, which prevents contamination of the films by material etched from the chamber or substrate. Mass spectrometry and optical emission spectrometry continuously monitor the process during growth. Laser interferometry has been used to measure the in situ deposition rate. The diamond films have been characterized by a variety of techniques including scanning electron microscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy, X-ray diffraction, laser ionization mass analysis, Raman scattering, IR spectroscopy and cathodoluminescence. These techniques show that the films contain only carbon and a low concentration of hydrogen, with no other impurities such as nitrogen or silicon.

Diamond and Related Materials, 2007

We present investigation of nanocrystalline diamond films deposited in a wide temperature range. The nanocrystalline diamond films were grown on silicon and glass substrates from hydrogen based gas mixture (methane and hydrogen) by microwave plasma CVD process. Film composition, nano-grain size and surface morphology were investigated by Raman spectroscopy and scanning electron microscopy. All samples showed diamond characteristic line centred at 1332 cm -1 in the Raman spectrum. Nanocrystalline diamond layers revealed high surface flatness (under 10 nm) with crystal size below 60 nm. Surface morphology of grown films was well homogeneous over glass substrates due to used mechanical seeding procedure. Very thin films (40 nm) were successfully grown on glass slides (i.e. standard size 1 × 3″). An increase in delay time was observed when the substrate temperature was decreased. A possible origin for this behaviour was discussed.

Surface and Coatings Technology, 2006

We present a study of the microstructural and electrical properties of nitrogen doped diamond (NDD) thin films deposited on Si(111) by microwave plasma enhanced chemical vapor deposition (MWCVD). The conductivity of NDD thin film increases with increasing bias. In contrast, we also found the conductivity decreased with the increasing growth temperature and the increasing thickness of the diamond film after longer deposition. According to the microstructural analysis of NDD thin films by means of SEM, we found that the thicker the diamond thin film is, the bigger the grain size of the diamond grows, and the fewer interfaces the grain boundary of the NDD has, yield to a larger resistance. We propose that the nitrogen in the NDD was not doped into diamond crystallines but was located in the interlayer of the grain boundaries of the NDD. D

Journal of Electron Spectroscopy and Related Phenomena, 2020

Ultra-nano-crystalline diamond (UNCD) thin films with average thickness ∼200 nm, were grown on n-type mirror polished silicon (100) substrates using microwave plasma enhanced chemical vapour deposition system in different gas (H 2-N 2-ArCH 4) composition plasma atmospheres at 1200 W (2.45 GHz) and in a pressure of 120 Torr with plasma-temperature ∼475°C. Raman spectroscopy was used for microstructural study and nanoindentation was used for Hardness/Young's modulus study; whereas X-ray absorption near edge structure, X-ray photoelectron and ultraviolet photoemission spectroscopies were used for electronic structure of UNCD thin films. The hardness of the films is found to be ∼30 GPa, Young's modulus ∼300 GPa and induced electron field emission, the turn on electric field, E TOE = 11 V/μm. All results show that the UNCD could be useful for different industrial semiconductor/optoelectronic devices and as flexible materials for thin film coating technology.

Journal of Materials Research, 1997

Diamond thin films grown from a dc-arc discharge in CH 4 ͞H 2 mixtures on Si wafers were examined by transmission electron microscopy and Raman spectroscopy. This deposition method provides good diamond crystallinity at high CH 4 concentrations (3% -9%). Seeding the substrate with 5 nm diamond particles at a density of 2 3 10 12 cm 21 followed by argon laser irradiation to reduce their agglomeration gives, just after starting deposition, a density of growth centers of 10 10 cm 22 . At 3% CH 4 concentration the film grows with almost perfect crystallites. Richer CH 4 mixtures (5% and 9%) produce crystallites with twins and stacking faults. An amorphous 20 -70 nm SiC interlayer is present at these CH 4 concentrations, which was not observed at 3% CH 4 . Amorphous sp 3 -and sp 2 -bonded carbon was detected by Raman spectroscopy at all CH 4 concentrations and correlated with TEM data.

Vacuum, 2010

The article presents results of structural studies of polycrystalline diamond thin films deposited by hot filament CVD on silicon substrates. The films were characterized using Scanning Electron Microscopy (SEM), Raman Spectroscopy (RS), Electron Backscattered Diffraction (EBSD), Energy Dispersive Spectroscopy (EDS) and Secondary Ion Mass Spectroscopy (SIMS). Both the EBSD patterns and Raman spectra confirm that the grains visible in the electron micrographs are diamond micro-crystallites. The residual stress in the films is found to be in the range between À4.29 GPa and À0.56 GPa depending on the sample thickness. No evidence of lonsdalite and graphite has been registered in the polycrystalline material of the investigated samples. Evidence of the existence of silicon carbide at the diamond/silicon interface is presented. It is also suggested that an amorphous carbonaceous film covers the silicon surface in the regions of holes in the thin diamond layers.