Diamond deposition in a bell-jar reactor: influence of the plasma and substrate parameters on the microstructure and growth rate

Experiments with a Langmuir probe and optical emission spectroscopy combined with actinometry are carried out in inductively coupled rf (13.56 MHz) Ar/H2 discharges at total pressures of 20 m, 40 m, and 60 mTorr in hydrogen fractions ranging from 0% to 50%. The measured electron energy probability functions (EEPFs), which deviate from the Maxwellian distributions owing to the depletion of high-energy electrons, can be approximated using two temperatures. The electron temperatures, which can be deduced from the slopes of low-energy and high-energy parts of the EEPFs, relatively abruptly increase with increasing the hydrogen fraction in the hydrogen fractions below 10%, whereas the measured electron density markedly decreases with increasing the hydrogen fraction in the hydrogen fractions below 20%. The effective ion mass, which can be estimated from the ion current collected into the probe, markedly decreases with increasing the hydrogen fraction. The density of hydrogen atoms estimated by actinometry markedly increases as molecular hydrogen is added to Ar discharges, and then gradually increases with increasing the hydrogen fraction at the hydrogen fractions higher than 10%–20%. A global model is used to study the effect of Ar dilution to hydrogen discharges on the plasma parameters assuming the Maxwellian electron energy distribution. The model results are compared with the experimental results, obtaining reasonably good agreement.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Properties of inductively coupled rf Ar/H2 plasmas: Experiment and global model

Kimura

Kasugai

2010

“…Microwave-plasma-enhanced CVD is a representative method for high-quality diamond growth. 17,18 Plasma torch is used to deposit diamond films with high deposition rate. 19 a͒ Other methods, such as fast heating, 20,21 optical pumping, [22][23][24] and substrate pretreatment, 25,26 have also been studied.…”

Section: Introductionmentioning

confidence: 99%

Enhanced chemical vapor deposition of diamond by wavelength-matched vibrational excitations of ethylene molecules using tunable CO2 laser irradiation

Líu

Xie

Gao

et al. 2009

Wavelength-matched vibrational excitations of ethylene ͑C 2 H 4 ͒ molecules using a tunable carbon dioxide ͑CO 2 ͒ laser were employed to significantly enhance the chemical vapor deposition ͑CVD͒ of diamond in open air using a precursor gas mixture of C 2 H 4 , acetylene ͑C 2 H 2 ͒, and oxygen ͑O 2 ͒. The CH 2 -wag vibration mode ͑ 7 ͒ of the C 2 H 4 molecules was selected to achieve the resonant excitation in the CVD process. Both laser wavelengths of 10.591 and 10.532 m were applied to the CVD processes to compare the C 2 H 4 excitations and diamond depositions. Compared with 10.591 m produced by common CO 2 lasers, the laser wavelength of 10.532 m is much more effective to excite the C 2 H 4 molecules through the CH 2 -wag mode. Under the laser irradiation with a power of 800 W and a wavelength of 10.532 m, the grain size in the deposited diamond films was increased by 400% and the film thickness was increased by 300%. The quality of the diamond crystals was also significantly enhanced.

“…15 The undoped and high resistivity (у10 11 ⍀ cm) polycrystalline CVD diamond was grown by microwave plasma enhanced CVD. 19,20 The CVD1 diamond was found to contain a low concentration of nitrogen impurities as determined by Raman spectroscopy, where a significant emission peak at 2052 cm Ϫ1 was apparent. 21 The Raman spectrum of CVD2 material showed no evidence of nitrogen incorporation.…”

Section: A Diamond Photodetectorsmentioning

confidence: 99%

Solar blind chemically vapor deposited diamond detectors for vacuum ultraviolet pulsed light-source characterization

Foulon

Bergonzo

Borel

et al. 1998

Self Cite

A major difficulty in characterizing vacuum ultraviolet (VUV) radiation produced by harmonic generation or four-wave sum frequency mixing arises in differentiating between the desired VUV signal and the remaining fundamental pump laser beam. To overcome this problem, visible and near UV blind VUV detectors, made from natural and synthetic diamond, have been developed. Such detectors have been used to characterize coherent VUV pulses (λ=125 nm, pulse duration at full width half maximum (FWHM) τFWHM∼7 ns) generated by resonance-enhanced four-wave sum mixing in mercury vapor. They allow full characterization of the intensity profile of the VUV pulses, without any significant parasitic signal from simultaneous stray light irradiation at λ=313 nm. Detectors were fabricated exhibiting response times of less than 70 ps at FWHM, corresponding to the lowest response time obtainable with a 7 GHz bandwidth single-shot oscilloscope.