为考察金刚石形成氢终止表面的反应机制,采用微波氢等离子体处理以及电阻丝氢气气氛加热处理进行对比研究.利用光发射谱(OES)和漫反射傅里叶变换红外光谱(DRIFTS)分别表征了微波氢等离子体中的活性基团和金刚石表面氢终止浓度.结果表明...为考察金刚石形成氢终止表面的反应机制,采用微波氢等离子体处理以及电阻丝氢气气氛加热处理进行对比研究.利用光发射谱(OES)和漫反射傅里叶变换红外光谱(DRIFTS)分别表征了微波氢等离子体中的活性基团和金刚石表面氢终止浓度.结果表明,微波氢等离子体环境下,随着衬底温度、等离子体密度和能量的增加,温度至700°C(800 W/3 k Pa)时,等离子体中出现了明显的CH基团;相应地,金刚石表面氢终止浓度随温度、等离子体密度和能量的增加而增加.采用氢气气氛下电阻丝加热的方法同样形成了氢终止金刚石表面,表明微波等离子体处理金刚石表面形成氢终止主要源于由温度控制的表面化学反应,而非等离子体的物理刻蚀作用.氧终止金刚石表面形成氢终止的机制是表面C=O键在高于500°C时分解为CO,相应的悬挂键由氢原子或氢分子占据.展开更多
The ohmic contact interface between diamond and metal is essential for the application of diamond detectors.Surface modification can significantly affect the contact performance and eliminate the interface polarizatio...The ohmic contact interface between diamond and metal is essential for the application of diamond detectors.Surface modification can significantly affect the contact performance and eliminate the interface polarization effect.However,the radiation stability of a diamond detector is also sensitive to surface modification.In this work,the influence of surface modification technology on a diamond ohmic contact under high-energy radiation was investigated.Before radiation,the specific contact resistivities(ρc)between Ti/Pt/Au-hydrogen-terminated diamond(H-diamond)and Ti/Pt/Au-oxygenterminated diamond(O-diamond)were 2.0×10^(-4)W·cm^(2) and 4.3×10^(-3)Wcm^(2),respectively.After 10 MeV electron radiation,the ρc of Ti/Pt/Au H-diamond and Ti/Pt/Au O-diamond were 5.3×10^(-3)W·cm^(2)and 9.1×10^(-3)W·cm^(2),respectively.The rates of change of ρc of H-diamond and O-diamond after radiation were 2550%and 112%,respectively.The electron radiation promotes bond reconstruction of the diamond surface,resulting in an increase in ρc.展开更多
In this study,uniform diamond films with a diameter of 100 mm were deposited in a 15 kW/2.45 GHz ellipsoidal microwave plasma chemical vapour deposition system.A phenomenological model previously developed by our grou...In this study,uniform diamond films with a diameter of 100 mm were deposited in a 15 kW/2.45 GHz ellipsoidal microwave plasma chemical vapour deposition system.A phenomenological model previously developed by our group was used to simulate the distribution of the electric strength and electron density of plasma.Results indicate that the electric field in the cavity includes multiple modes,i.e.TM_(02) and TM_(03).When the gas pressure exceeds 10 kPa,the electron density of plasma increases and plasma volume decreases.A T-shaped substrate was developed to achieve uniform temperature,and the substrate was suspended in air fromφ70 to 100 mm,thus eliminating vertical heat dissipation.An edge electric field was added to the system after the introduction of the T-shaped substrate.Moreover,the plasma volume in this case was greater than that in the central electric field but smaller than that in the periphery electric field of the TM_(02) mode.This indicates that the electric field above and below the edge benefits the plasma volume rather than the periphery electric field of the TM_(02) mode.The quality,uniformity and surface morphology of the deposited diamond films were primarily investigated to maintain substrate temperature uniformity.When employing the improved substrate,the thickness unevenness of theφ100 mm diamond film decreased from 22%to 7%.展开更多
The effect of the substrate holder feature dimensions on plasma density（ne）, power density（Qmw） and gas temperature（T） of a discharge marginal plasma（a plasma caused by marginal discharge） and homogeneous plas...The effect of the substrate holder feature dimensions on plasma density（ne）, power density（Qmw） and gas temperature（T） of a discharge marginal plasma（a plasma caused by marginal discharge） and homogeneous plasma were investigated for the microwave plasma chemical vapor deposition process. Our simulations show that decreasing the dimensions of the substrate holder in a radical direction and increasing its dimension in the direction of the axis helps to produce marginally inhomogeneous plasma. When the marginal discharge appears, the maximum plasma density and power density appear at the edge of the substrate. The gas temperature increases until a marginally inhomogeneous plasma develops. The marginally inhomogeneous plasma can be avoided using a movable substrate holder that can tune the plasma density, power density and gas temperature. It can also ensure that the power density and electron density are as high as possible with uniform distribution of plasma. Moreover, both inhomogeneous and homogeneous diamond films were prepared using a new substrate holder with a diameter of 30 mm. The observation of inhomogeneous diamond films indicates that the marginal discharge can limit the deposition rate in the central part of the diamond film. The successfully produced homogeneous diamond films show that by using a substrate holder it is possible to deposit diamond film at 7.2 μm h^（–1）at 2.5 kW microwave power.展开更多
To explain the stabilization mechanism of the carbon-ion-implanted GaN under the diamond growth environment,the luminescence characteristics and structure evolution correlative with sites'carbon atoms located for ...To explain the stabilization mechanism of the carbon-ion-implanted GaN under the diamond growth environment,the luminescence characteristics and structure evolution correlative with sites'carbon atoms located for highfluence carbon-ion-implanted Ga N are discussed.GaN is implanted with carbon ion using fluence of 2×10^(17)cm^(-2)and energy of 45 keV.Then the implanted samples are annealed at 800℃for 20 min and 1 h under the N_(2) atmosphere.The luminescence characteristics of carbon-ion-implanted GaN are evaluated by photoluminescence spectrum at wavelength 325 nm.The lattice damage of Ga N is characterized by Raman spectrum and the corresponding vacancy-defect evolution before and after annealing is measured by slow positron annihilation.The results show that most of the carbon atoms will be located at the interstitial sites after carbon ion implantation due to the weak mobility.As the implanted samples are annealed,strong yellow luminescence is emitted and the vacancies for Ga(V_(Ga))are reduced resulting from the migration of interstitial carbon(C_(i))and formation of complexes(CGaand/or C_(Ga)-C_(i))between them.As the annealing time is prolonged,the carbon ions accommodated by the vacancies are saturated,vacancy clusters with carbon atoms appear and the concentration of C_(Ga)diminishes,which will have an adverse effect on the diamond film nucleation and growth.展开更多
文摘为考察金刚石形成氢终止表面的反应机制,采用微波氢等离子体处理以及电阻丝氢气气氛加热处理进行对比研究.利用光发射谱(OES)和漫反射傅里叶变换红外光谱(DRIFTS)分别表征了微波氢等离子体中的活性基团和金刚石表面氢终止浓度.结果表明,微波氢等离子体环境下,随着衬底温度、等离子体密度和能量的增加,温度至700°C(800 W/3 k Pa)时,等离子体中出现了明显的CH基团;相应地,金刚石表面氢终止浓度随温度、等离子体密度和能量的增加而增加.采用氢气气氛下电阻丝加热的方法同样形成了氢终止金刚石表面,表明微波等离子体处理金刚石表面形成氢终止主要源于由温度控制的表面化学反应,而非等离子体的物理刻蚀作用.氧终止金刚石表面形成氢终止的机制是表面C=O键在高于500°C时分解为CO,相应的悬挂键由氢原子或氢分子占据.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFB3608601).
文摘The ohmic contact interface between diamond and metal is essential for the application of diamond detectors.Surface modification can significantly affect the contact performance and eliminate the interface polarization effect.However,the radiation stability of a diamond detector is also sensitive to surface modification.In this work,the influence of surface modification technology on a diamond ohmic contact under high-energy radiation was investigated.Before radiation,the specific contact resistivities(ρc)between Ti/Pt/Au-hydrogen-terminated diamond(H-diamond)and Ti/Pt/Au-oxygenterminated diamond(O-diamond)were 2.0×10^(-4)W·cm^(2) and 4.3×10^(-3)Wcm^(2),respectively.After 10 MeV electron radiation,the ρc of Ti/Pt/Au H-diamond and Ti/Pt/Au O-diamond were 5.3×10^(-3)W·cm^(2)and 9.1×10^(-3)W·cm^(2),respectively.The rates of change of ρc of H-diamond and O-diamond after radiation were 2550%and 112%,respectively.The electron radiation promotes bond reconstruction of the diamond surface,resulting in an increase in ρc.
基金sponsored by National Key Research and Development Program of China(No.2019YFE03100200)National Natural Science Foundation of China(No.5210020483)+1 种基金Postdoc Research Foundation of Shunde Graduate School of University of Science and Technology Beijing(No.2020BH015)Fundamental Research Funds for the Central Universities(No.FRF-MP-20-48)。
文摘In this study,uniform diamond films with a diameter of 100 mm were deposited in a 15 kW/2.45 GHz ellipsoidal microwave plasma chemical vapour deposition system.A phenomenological model previously developed by our group was used to simulate the distribution of the electric strength and electron density of plasma.Results indicate that the electric field in the cavity includes multiple modes,i.e.TM_(02) and TM_(03).When the gas pressure exceeds 10 kPa,the electron density of plasma increases and plasma volume decreases.A T-shaped substrate was developed to achieve uniform temperature,and the substrate was suspended in air fromφ70 to 100 mm,thus eliminating vertical heat dissipation.An edge electric field was added to the system after the introduction of the T-shaped substrate.Moreover,the plasma volume in this case was greater than that in the central electric field but smaller than that in the periphery electric field of the TM_(02) mode.This indicates that the electric field above and below the edge benefits the plasma volume rather than the periphery electric field of the TM_(02) mode.The quality,uniformity and surface morphology of the deposited diamond films were primarily investigated to maintain substrate temperature uniformity.When employing the improved substrate,the thickness unevenness of theφ100 mm diamond film decreased from 22%to 7%.
基金sponsored by National Natural Science Foundation of China(NSFC)(No.51272024)the PhD Programs Foundation of Ministry of Education of China(No.20110006110011)
文摘The effect of the substrate holder feature dimensions on plasma density（ne）, power density（Qmw） and gas temperature（T） of a discharge marginal plasma（a plasma caused by marginal discharge） and homogeneous plasma were investigated for the microwave plasma chemical vapor deposition process. Our simulations show that decreasing the dimensions of the substrate holder in a radical direction and increasing its dimension in the direction of the axis helps to produce marginally inhomogeneous plasma. When the marginal discharge appears, the maximum plasma density and power density appear at the edge of the substrate. The gas temperature increases until a marginally inhomogeneous plasma develops. The marginally inhomogeneous plasma can be avoided using a movable substrate holder that can tune the plasma density, power density and gas temperature. It can also ensure that the power density and electron density are as high as possible with uniform distribution of plasma. Moreover, both inhomogeneous and homogeneous diamond films were prepared using a new substrate holder with a diameter of 30 mm. The observation of inhomogeneous diamond films indicates that the marginal discharge can limit the deposition rate in the central part of the diamond film. The successfully produced homogeneous diamond films show that by using a substrate holder it is possible to deposit diamond film at 7.2 μm h^（–1）at 2.5 kW microwave power.
基金Supported by the National Natural Science Foundation of China under Grant No 51402013the National Key Research and Development Program of China under Grant No 2016YFE0133200the European Union’s Horizon 2020 Research and Innovation Staff Exchange Scheme under Grant No 734578
文摘To explain the stabilization mechanism of the carbon-ion-implanted GaN under the diamond growth environment,the luminescence characteristics and structure evolution correlative with sites'carbon atoms located for highfluence carbon-ion-implanted Ga N are discussed.GaN is implanted with carbon ion using fluence of 2×10^(17)cm^(-2)and energy of 45 keV.Then the implanted samples are annealed at 800℃for 20 min and 1 h under the N_(2) atmosphere.The luminescence characteristics of carbon-ion-implanted GaN are evaluated by photoluminescence spectrum at wavelength 325 nm.The lattice damage of Ga N is characterized by Raman spectrum and the corresponding vacancy-defect evolution before and after annealing is measured by slow positron annihilation.The results show that most of the carbon atoms will be located at the interstitial sites after carbon ion implantation due to the weak mobility.As the implanted samples are annealed,strong yellow luminescence is emitted and the vacancies for Ga(V_(Ga))are reduced resulting from the migration of interstitial carbon(C_(i))and formation of complexes(CGaand/or C_(Ga)-C_(i))between them.As the annealing time is prolonged,the carbon ions accommodated by the vacancies are saturated,vacancy clusters with carbon atoms appear and the concentration of C_(Ga)diminishes,which will have an adverse effect on the diamond film nucleation and growth.
