High-quality type IIa large diamond crystals are synthesized with Ti/Cu as nitrogen getter doped in an FeNi–C system at temperature ranging from 1230℃to 1380℃and at pressure 5.3–5.9 GPa by temperature gradient met...High-quality type IIa large diamond crystals are synthesized with Ti/Cu as nitrogen getter doped in an FeNi–C system at temperature ranging from 1230℃to 1380℃and at pressure 5.3–5.9 GPa by temperature gradient method.Different ratios of Ti/Cu are added to the Fe Ni–C system to investigate the best ratio for high-quality type IIa diamond.Then,the different content of nitrogen getter Ti/Cu(Ti:Cu=4:3)is added to this synthesis system to explore the effect on diamond growth.The macro and micro morphologies of synthesized diamonds with Ti/Cu added,whose nitrogen concentration is determined by Fourier transform infrared(FTIR),are analyzed by optical microscopy(OM)and scanning electron microscopy(SEM),respectively.It is found that the inclusions in the obtained crystals are minimal when the Ti/Cu ratio is 4:3.Furthermore,the temperature interval for diamond growth becomes narrower when using Ti as the nitrogen getter.Moreover,the lower edge of the synthesis temperature of type IIa diamond is 25℃higher than that of type Ib diamond.With the increase of the content of Ti/Cu(Ti:Cu=4:3),the color of the synthesized crystals changes from yellow and light yellow to colorless.When the Ti/Cu content is 1.7 wt%,the nitrogen concentration of the crystal is less than 1 ppm.The SEM results show that the synthesized crystals are mainly composed by(111)and(100)surfaces,including(311)surface,when the nitrogen getter is added into the synthesis system.At the same time,there are triangular pits and dendritic growth stripes on the crystal surface.This work will contribute to the further research and development of high-quality type IIa diamond.展开更多
High-quality p-type boron-doped IIb diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K. The mo...High-quality p-type boron-doped IIb diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K. The morphologies and surface textures of the synthetic diamond crystals with different boron additive quantities are characterized by using an optical microscope and a scanning electron microscope respectively. The impurities of nitrogen and boron in diamonds are detected by micro Fourier transform infrared technique. The electrical properties including resistivities, Hall coefficients, Hall mobilities and carrier densities of the synthesized samples are measured by a four-point probe and the Hall effect method. The results show that large p-type boron-doped diamond single crystals with few nitrogen impurities have been synthesized. With the increase of quantity of additive boron, some high-index crystal faces such as {113} gradually disappear, and some stripes and triangle pits occur on the crystal surface. This work is helpful for the further research and application of boron-doped semiconductor diamond.展开更多
In order to synthesize high-quality type-Ⅱa large diamond, the selection of catalyst is very important, in addition to the nitrogen getter. In this paper, type-IIa large diamonds are grown under high pressure and hig...In order to synthesize high-quality type-Ⅱa large diamond, the selection of catalyst is very important, in addition to the nitrogen getter. In this paper, type-IIa large diamonds are grown under high pressure and high temperature（HPHT） by using the temperature gradient method（TGM）, with adopting Ti/Cu as the nitrogen getter in Ni70Mn25Co5（abbreviated as NiMnCo） or Fe（55）Ni（29）Co（16）（abbreviated FeNiCo） catalyst. The values of nitrogen concentration（Nc） in both synthesized high-quality diamonds are less than 1 ppm, when Ti/Cu（1.6 wt%） is added in the FeNiCo or Ti/Cu（1.8 wt%） is added in the NiMnCo. The difference in solubility of nitrogen between both catalysts at HPHT is the basic reason for the different effect of Ti/Cu on eliminating nitrogen. The nitrogen-removal efficiency of Ti/Cu in the NiMnCo catalyst is less than in the FeNiCo catalyst. Additionally, a high-quality type-Ⅱa large diamond size of 5.0 mm is obtained by reducing the growth rate and keeping the nitrogen concentration of the diamond to be less than 1 ppm, when Ti/Cu（1.6 wt%） is added in the FeNiCo catalyst.展开更多
Diamond thin films were prepared in a modified quartz bell-jar type microwave chemical vapor deposition (MWPCVD) system. The influences of process parameters on MWPCVD diamond thin films quality such as substrate pre...Diamond thin films were prepared in a modified quartz bell-jar type microwave chemical vapor deposition (MWPCVD) system. The influences of process parameters on MWPCVD diamond thin films quality such as substrate pretreatment, deposition gas ratio, deposition pressure and substrate position were examined and studied. The deposited films were characterized by using Scanning electron microscopy(SEM) and Raman spectroscopy. It was shown that this quartz bell-jar type MWPCVD system is beneficial to the deposition of high quality diamond thin films.展开更多
In this paper, we have reported an investigation on the evolution of nitrogen structures in diamond crystals which contain nitrogen donor atoms in the range of 1500 ppm-1600 ppm following an annealing treatment at a h...In this paper, we have reported an investigation on the evolution of nitrogen structures in diamond crystals which contain nitrogen donor atoms in the range of 1500 ppm-1600 ppm following an annealing treatment at a high pressure of about 6.5 GPa and high temperatures of 1920 K-2120 K. The annealing treatment was found to completely transform nitrogen atoms originally arranged in a single substitutional form （C-center）, into a pair form （A-center）, indicated from infrared （IR） spectra. The photoluminescence （PL） spectra revealed that a small fraction of nitrogen atoms remained in C-center form, while some nitrogen atoms in A-center form were further transformed into N3 and H3 center structures. In addition, PL spectra have revealed the existence of two newly observed nitrogen-related structures with zero phonon lines at 611 nm and 711 nm. All these findings above are very helpful in understanding the formation mechanism of natural diamond stones of the Ia-type, which contains nitrogen atoms in an aggregated form.展开更多
Oxygen-doped diamond films are prepared by implanting various dose oxygen ions into the diamond films synthesized by hot filament chemical vapour deposition, and their electrical and structural properties are investig...Oxygen-doped diamond films are prepared by implanting various dose oxygen ions into the diamond films synthesized by hot filament chemical vapour deposition, and their electrical and structural properties are investigated. Hall effect measurements show that lower dose oxygen ion implantation is beneficial to preparing n-type diamonds. The carrier concentration increases with the dose increasing, indicating that oxygen ions supply electrons to the diamonds. The results of AES spectrum indicate that oxygen ions are doped into the diamond films, and the O-implanted depth is around 0.1μm. Raman spectrum measurements indicate that the lower dose oxygen ion implantation at 10^14 cm^-2 or 10^15 cm^-2 is favourable for producing less damaged O-doDed diamond films.展开更多
We report our observations on the higher carrier mobility and higher conductivity of sulfur-doped n-type diamond thin films synthesized by the hot filament chemical vapor deposi- tion （HFCVD）. The structural and ele...We report our observations on the higher carrier mobility and higher conductivity of sulfur-doped n-type diamond thin films synthesized by the hot filament chemical vapor deposi- tion （HFCVD）. The structural and electrical characterizations of the films are measured by X-ray diffraction （XRD）, Raman spectroscopy, scanning electron microscope （SEM）, energy dispersion X-ray spectra （EDX）, and Hall effect measurements. It is found that the sulfur atoms are in- corporated into the polycrystalline diamond films. The n-type conductivity of the films increases with the H2S concentration, and a conductivity of the films as high as 1.82 ^-l.cm-1 is achieved. The results show that the sulfur atom plays an important role in the structural and electrical properties of sulfur-doped diamond thin films.展开更多
基于高温高压合成金刚石过程中铁基触媒及其金属包膜中存在大量Fe3C型碳化物的实验结果,利用余氏理论(empirical electron theory of solid and molecule,EET)分析了Fe3C型碳化物内C-C键组成晶面和与之对应的金刚石晶面的共价电子密度,...基于高温高压合成金刚石过程中铁基触媒及其金属包膜中存在大量Fe3C型碳化物的实验结果,利用余氏理论(empirical electron theory of solid and molecule,EET)分析了Fe3C型碳化物内C-C键组成晶面和与之对应的金刚石晶面的共价电子密度,发现它们在一级近似下存在连续性,满足程氏理论(improved Thomas-Fermi-Dirac theory advanced by Cheng,TFDC)提出的原子界面边界条件。分析结果表明:高温高压下的金刚石单晶生长与 Fe3C型碳化物的分解有关。在4种Fe3C型碳化物中,(Fe,Ni)3C内的C-C键组成晶面和与之对应的金刚石晶面的共价电子密度连续的组数最多。因而认为:合成金刚石过程中使用含镍的铁基触媒,在高温高压下形成的(Fe,Ni)3C作为碳源,最容易转变为金刚石。展开更多
基金Project supported by the Natural Science Foundation of Henan Province of China(Grant No.182300410279)the Key Science and Technology Research Project of Henan Province of China(Grant No.182102210311)+2 种基金the Key Scientific Research Project in Colleges and Universities of Henan Province of China(Grant Nos.18A430017 and 20B140009)the Fundamental Research Funds for the Universities of Henan Province of China(Grant No.NSFRF180408)the Fund for the Innovative Research Team(in Science and Technology)in the University of Henan Province of China(Grant No.19IRTSTHN027)
文摘High-quality type IIa large diamond crystals are synthesized with Ti/Cu as nitrogen getter doped in an FeNi–C system at temperature ranging from 1230℃to 1380℃and at pressure 5.3–5.9 GPa by temperature gradient method.Different ratios of Ti/Cu are added to the Fe Ni–C system to investigate the best ratio for high-quality type IIa diamond.Then,the different content of nitrogen getter Ti/Cu(Ti:Cu=4:3)is added to this synthesis system to explore the effect on diamond growth.The macro and micro morphologies of synthesized diamonds with Ti/Cu added,whose nitrogen concentration is determined by Fourier transform infrared(FTIR),are analyzed by optical microscopy(OM)and scanning electron microscopy(SEM),respectively.It is found that the inclusions in the obtained crystals are minimal when the Ti/Cu ratio is 4:3.Furthermore,the temperature interval for diamond growth becomes narrower when using Ti as the nitrogen getter.Moreover,the lower edge of the synthesis temperature of type IIa diamond is 25℃higher than that of type Ib diamond.With the increase of the content of Ti/Cu(Ti:Cu=4:3),the color of the synthesized crystals changes from yellow and light yellow to colorless.When the Ti/Cu content is 1.7 wt%,the nitrogen concentration of the crystal is less than 1 ppm.The SEM results show that the synthesized crystals are mainly composed by(111)and(100)surfaces,including(311)surface,when the nitrogen getter is added into the synthesis system.At the same time,there are triangular pits and dendritic growth stripes on the crystal surface.This work will contribute to the further research and development of high-quality type IIa diamond.
基金supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 51001042)the Doctor Foundation of the Henan Polytechnic University,China (Grant No. 2010-32)
文摘High-quality p-type boron-doped IIb diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K. The morphologies and surface textures of the synthetic diamond crystals with different boron additive quantities are characterized by using an optical microscope and a scanning electron microscope respectively. The impurities of nitrogen and boron in diamonds are detected by micro Fourier transform infrared technique. The electrical properties including resistivities, Hall coefficients, Hall mobilities and carrier densities of the synthesized samples are measured by a four-point probe and the Hall effect method. The results show that large p-type boron-doped diamond single crystals with few nitrogen impurities have been synthesized. With the increase of quantity of additive boron, some high-index crystal faces such as {113} gradually disappear, and some stripes and triangle pits occur on the crystal surface. This work is helpful for the further research and application of boron-doped semiconductor diamond.
基金supported by the National Natural Science Foundation of China(Grant No.11604246)the China Postdoctoral Science Foundation(Grant No.2016M592714)+2 种基金the Professional Practice Demonstration Base for Professional Degree Graduate in Material Engineering of Henan Polytechnic University,China(Grant No.2016YJD03)the Funds from the Education Department of Henan Province,China(Grant Nos.12A430010 and 17A430020)the Project for Key Science and Technology Research of Henan Province,China(Grant No.162102210275)
文摘In order to synthesize high-quality type-Ⅱa large diamond, the selection of catalyst is very important, in addition to the nitrogen getter. In this paper, type-IIa large diamonds are grown under high pressure and high temperature（HPHT） by using the temperature gradient method（TGM）, with adopting Ti/Cu as the nitrogen getter in Ni70Mn25Co5（abbreviated as NiMnCo） or Fe（55）Ni（29）Co（16）（abbreviated FeNiCo） catalyst. The values of nitrogen concentration（Nc） in both synthesized high-quality diamonds are less than 1 ppm, when Ti/Cu（1.6 wt%） is added in the FeNiCo or Ti/Cu（1.8 wt%） is added in the NiMnCo. The difference in solubility of nitrogen between both catalysts at HPHT is the basic reason for the different effect of Ti/Cu on eliminating nitrogen. The nitrogen-removal efficiency of Ti/Cu in the NiMnCo catalyst is less than in the FeNiCo catalyst. Additionally, a high-quality type-Ⅱa large diamond size of 5.0 mm is obtained by reducing the growth rate and keeping the nitrogen concentration of the diamond to be less than 1 ppm, when Ti/Cu（1.6 wt%） is added in the FeNiCo catalyst.
文摘Diamond thin films were prepared in a modified quartz bell-jar type microwave chemical vapor deposition (MWPCVD) system. The influences of process parameters on MWPCVD diamond thin films quality such as substrate pretreatment, deposition gas ratio, deposition pressure and substrate position were examined and studied. The deposited films were characterized by using Scanning electron microscopy(SEM) and Raman spectroscopy. It was shown that this quartz bell-jar type MWPCVD system is beneficial to the deposition of high quality diamond thin films.
基金Project supported by the Natural Science Foundation of Heilongjiang Province,China(Grant No.E201341)the Open Research Program of Key Lab of Superhard Materials of Mudanjiang Normal College,China(Grant No.201302)
文摘In this paper, we have reported an investigation on the evolution of nitrogen structures in diamond crystals which contain nitrogen donor atoms in the range of 1500 ppm-1600 ppm following an annealing treatment at a high pressure of about 6.5 GPa and high temperatures of 1920 K-2120 K. The annealing treatment was found to completely transform nitrogen atoms originally arranged in a single substitutional form （C-center）, into a pair form （A-center）, indicated from infrared （IR） spectra. The photoluminescence （PL） spectra revealed that a small fraction of nitrogen atoms remained in C-center form, while some nitrogen atoms in A-center form were further transformed into N3 and H3 center structures. In addition, PL spectra have revealed the existence of two newly observed nitrogen-related structures with zero phonon lines at 611 nm and 711 nm. All these findings above are very helpful in understanding the formation mechanism of natural diamond stones of the Ia-type, which contains nitrogen atoms in an aggregated form.
文摘Oxygen-doped diamond films are prepared by implanting various dose oxygen ions into the diamond films synthesized by hot filament chemical vapour deposition, and their electrical and structural properties are investigated. Hall effect measurements show that lower dose oxygen ion implantation is beneficial to preparing n-type diamonds. The carrier concentration increases with the dose increasing, indicating that oxygen ions supply electrons to the diamonds. The results of AES spectrum indicate that oxygen ions are doped into the diamond films, and the O-implanted depth is around 0.1μm. Raman spectrum measurements indicate that the lower dose oxygen ion implantation at 10^14 cm^-2 or 10^15 cm^-2 is favourable for producing less damaged O-doDed diamond films.
基金supported by the Fundamental Research Funds for Central Universities of China(No.10ML40)
文摘We report our observations on the higher carrier mobility and higher conductivity of sulfur-doped n-type diamond thin films synthesized by the hot filament chemical vapor deposi- tion （HFCVD）. The structural and electrical characterizations of the films are measured by X-ray diffraction （XRD）, Raman spectroscopy, scanning electron microscope （SEM）, energy dispersion X-ray spectra （EDX）, and Hall effect measurements. It is found that the sulfur atoms are in- corporated into the polycrystalline diamond films. The n-type conductivity of the films increases with the H2S concentration, and a conductivity of the films as high as 1.82 ^-l.cm-1 is achieved. The results show that the sulfur atom plays an important role in the structural and electrical properties of sulfur-doped diamond thin films.
文摘基于高温高压合成金刚石过程中铁基触媒及其金属包膜中存在大量Fe3C型碳化物的实验结果,利用余氏理论(empirical electron theory of solid and molecule,EET)分析了Fe3C型碳化物内C-C键组成晶面和与之对应的金刚石晶面的共价电子密度,发现它们在一级近似下存在连续性,满足程氏理论(improved Thomas-Fermi-Dirac theory advanced by Cheng,TFDC)提出的原子界面边界条件。分析结果表明:高温高压下的金刚石单晶生长与 Fe3C型碳化物的分解有关。在4种Fe3C型碳化物中,(Fe,Ni)3C内的C-C键组成晶面和与之对应的金刚石晶面的共价电子密度连续的组数最多。因而认为:合成金刚石过程中使用含镍的铁基触媒,在高温高压下形成的(Fe,Ni)3C作为碳源,最容易转变为金刚石。
