• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.3
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• pp.119-123
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• 2013

Most of the world's solar cells in photovoltaic industry are currently fabricated using crystalline silicon. Czochralski-grown silicon crystals are more expensive than multicrystalline silicon crystals. The future of solar-grade Czochralski-grown silicon crystals crucially depends on whether it is usable for the mass-production of high-efficiency solar cells or not. It is generally believed that the main obstacle for making solar-grade Czochralski-grown silicon crystals a perfect high-efficiency solar cell material is presently light-induced degradation problem. In this work, the substitution of boron with gallium in p-type silicon single crystal is studied as an alternative to reduce the extent of lifetime degradation. The diamond-wire sawing technology is employed to slice the silicon ingot. In this paper, the quality of the diamond wire-sawn gallium-doped silicon wafers is studied from the chemical, electrical and structural points of view. It is found that the characteristic of gallium-doped silicon wafers including texturing behavior and surface metallic impurities are same as that of conventional boron-doped Czochralski crystals.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.2
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• pp.40-45
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• 2018

We report Optically-Detected Magnetic Resonance (ODMR) study on Nitrogen-Vacancy (NV) centers in diamond. The experiment can easily be conducted with basic optics and microwave components. A diamond crystal having a high-density NV center is suitable for the ODMR study. The magnetic field dependence of ODMR spectrum allowed us to determine the orientation of the diamond crystal. In addition, we measured the variation of the ODMR spectrum as a function of the excitation laser power. Thermal heating induced by optical absorption caused the monotonic decrease of zero field splitting. The contrast of the ODMR peak, however, increased and, then, began to decrease, indicating the optimal laser power for recording the ODMR spectrum.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.4
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• pp.441-445
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• 1999

Thick diamond film having $~700\mu\textrm{m}$ thickness was deposited on polycrystalline molybdenum(Mo) substrate using high power (4 kW) microwave plasma-enhanced chemical vapor depostion (MPECVD) system. We could achieve free-standing diamond film via detaching as-deposited diamond film from the substrate by rapid cooling them under vacuum. We investigated the variation of photoconductivity after exposing the film surface to either oxygen or hydrogen plasma. At as-grown state, the growth side (the as-grown surface of the film) showed noticeable photoconcuctivity. The oxygen plasma treatment of this side led to the insulator. After exposing the film surface to hydrogen plasma, on the other hand, we could observe the reappearing of photoconductivity at the growth side. Based on these results, we suggest that the hydrogen plasma treatment may enhance the photoconductivity of free-standing diamond film.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.5
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• pp.171-174
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• 2016

The diamond wire sawing method to produce silicon wafers for the photovoltaic application is still a new and highly investigated wafering technology. This technology, featured as the higher productivity, lower wear of the wire, and easier recycling of the coolant, is expected to become the mainstream technique for slicing the silicon crystals. However, the saw marks on the wafer surface have to be investigated and improved. This paper discusses the removal of saw marks on diamond wire-sawn single crystalline silicon wafer. With a pretreatment step using tetramethyl ammonium hydroxide ($(CH_3)_4NOH$, TMAH) and conventional texturing process with KOH solution (1 % KOH, 8 % IPA, and DI water), the saw marks on the surface of the diamond wire-sawn silicon wafers can be effectively removed and they are invisible to naked eyes completely.

• The Korean Journal of Ceramics
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• v.3 no.1
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• pp.13-17
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• 1997

It is identified that the diamond films grown o bias-treated (100) silicon showed different surface morphologies and film textures according to the initial applied dc bias voltage at the same growth condition. The highly oriented diamond film (HODF) was successfully grown on -200 V bias-treated silicon substrate in which the heteroepitaxial relation of $(100)_{dimond}//(100)_{si}\; and\; [110]_{diamond}//[110]_{si}$ was identified. On the contrary, the heteroepitaxial relation was considerably disturbed in the samples bias-voltage was a key factor in growing the highly oriented diamond film on (100) silicon substrate. Considering the experimental results, we proposed a new model about heteroepitaxial diamond growth on silicon, in which 9 diamond unit cell are matched with 4 silicon cells and the bond covalency of both atoms is satisfied via the intermediate layer at the interface as well.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.2
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• pp.100-104
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• 2000

Diamond film was deposited on Si substrate by using microwave plasma-enhanced chemical vapor deposition (MPECVD) system. After thinning the cross section between diamond film and Si substrate by ion milling method, we investigated its interface via transmission electron microscopy We could observe that the diamond film was grown either directly on Si substrate or via the interlayer between diamond film and Si substrate. Thickness of the interlayer was varied along the cross section. The interlayer might mainly composed of Sic andlor amorphous carbon. We could observe the well-developed electron diffraction pattern of both Si and diamond around the interface. Based on this result, we can conjecture the initial growth behavior of diamond film on Si substrate.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.40-46
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• 2008

Ultraprecision cutting of steels with geometrically defined single crystal diamond tools is handicapped by excessive tool wear. This paper presents a new approach to suppress the wear of single crystal diamond tool in cutting of steels. In general, it is said that the wear of diamond tool is caused by chemically reactive wear under high temperature and high pressure conditions. In order to suppress such chemical reactions, the time of contact between the diamond tool and the steel work in cutting was controlled by employing the intermittent cutting method such as fly-cutting. Series of intermittent cutting experiments have been carried out to control the tool-work contact time by changing one cycle of cutting length and cutting speed. The experimental results were shown that the tool wear was much dependent on the contact time regardless of the cutting speed, and that the wear was much suppressed by reducing the tool-work contact time. It is expected that the steels can be successfully cut with a single crystal diamond tool by controlling the contact time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.192-195
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• 2019

Single-crystal diamond obtained by chemical vapor deposition (CVD) exhibits great potential for use in next-generation power devices. Low defect density is required for the use of such power devices in high-power operations; however, plastic deformation and lattice strain increase the dislocation density during diamond growth by CVD. Therefore, characterization of the dislocations in CVD diamond is essential to ensure the growth of high-quality diamond. In this work, we analyze the characteristics of the dislocations in CVD diamond through synchrotron white beam X-ray topography. In estimate, many threading edge dislocations and five mixed dislocations were identified over the whole surface.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.92-99
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• 1994

Diamond thin film was deposited on n type (100) Si substrate by MPECVD(Microwave plasma Enhanced Chemical Vapor Deposition). For the increase in nucleation density of diamond, Si substrate was pretreated by diamond powder or negative bias voltage was applied to the substrate during the initial deposition. In the case of retreated Si substrate, the diamond thin film quality was enhanced with increasing the total pressure in the range of 20~150 Torr. For the negative bias voltage, the formation condition of the diamond was seriously affected by $CH_4$ concentration and total pressure. The formation condition will be discussed with electrical current of substrate generated by plasma ions which depend on $CH_4$concentration, bias voltage, and total pressure.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.188-192
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• 2015

Gemological and spectroscopic properties of HPHT synthetic diamonds from New Diamond Technology (NDT) company in St. Petersburg (Russia) were examined. Their color (colorless, near-colorless with some boron and Fancy blue with high boron content) and clarity ($VVS-SI_1$) grades were comparable to those of top natural diamonds. NDT synthetic diamonds fluoresced and phosphoresced blue or orange under SWUV light. Photoluminescence spectra revealed H3 center with very small intensity and NV centers. The intensity of H3 in NDT synthetic diamond has very weak in comparison with natural one. Using a combination of gemological and spectroscopic tests, gem-quality synthetic diamonds from NDT can be distinguished from natural diamonds of similar quality.