Isothermal and cyclic oxidation behaviours of pure and yttrium-implanted nickel were studied at 1000℃ in air. Scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM) were used to examine...Isothermal and cyclic oxidation behaviours of pure and yttrium-implanted nickel were studied at 1000℃ in air. Scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM) were used to examine the micro-morphology and structure of oxide scales formed on the nickel substrate. It was found that Y-implantation significantly improved the anti- oxidation ability of nickel in both isothermal and cyclic oxidizing experiments. Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium. The main reason for the improvement in anti-oxidation of nickel was that Y- implantation greatly reduced the growing speed and grain size of NiO. This fine-grained NiO oxide film might have better high temperature plasticity and could relieve parts of compressive stress by means of creeping, and maintained a ridge character and a relatively low internal stress level. Hence yttrium ion-implantation remarkably enhanced the adhesion of protective NiO oxide scale formed on the nickel substrate.展开更多
Silver foils and ion-implanted silver foils exposed to atomic oxygen (AO) generated in a ground simulation facility were investigated by the quartz crystal microbalance (QCM), the scanning electron microscopy (SE...Silver foils and ion-implanted silver foils exposed to atomic oxygen (AO) generated in a ground simulation facility were investigated by the quartz crystal microbalance (QCM), the scanning electron microscopy (SEM) and the X-ray photoelectron spectroscopy (XPS). The experimental results show the presence of Ag2O and AgO in an oxidation process of the silver foil having exposure to AO. As soon as silver comes under the bombardment of atomic oxygen, the oxidation process starts with a thick film forming on the silver surface. Because of the development of stresses, the oxide layer gets cracked and spalled, which leads to appearance of a new silver surface intensifying further oxidation. At last, AgO begins to form on the outer surface of the oxide film. The analytical results of the XPS and the AES attest to formation of a continuous high-quality protective oxide-based layer on the surface of ion-implanted silver films after exposure to AO. This layer can well protect materials in question from erosion.展开更多
From the theoretical analysis of the thermionic emission model of current-voltage characteristics, this paper extracts the parameters for the gate Schottky contact of two ion-implanted 4H-SiC metal-semiconductor field...From the theoretical analysis of the thermionic emission model of current-voltage characteristics, this paper extracts the parameters for the gate Schottky contact of two ion-implanted 4H-SiC metal-semiconductor field-effect transistors (sample A and sample B for three and four times multiple ion-implantation channel region respectively) fabricated in the experiment, including the ideality factor, the series resistance, the zero-field barrier height, the interface oxide capacitance, the interface state density distribution, the neutral level of interface states and the fixed space charge density. The methods to improve the interface of the ion-implanted Schottky contact are given at last.展开更多
Ion-implantation layers are fabricated by multiple nitrogen ion-implantations (3 times for sample A and 4 times for sample B) into a p-type 4H-SiC epitaxial layer. The implantation depth profiles are calculated by u...Ion-implantation layers are fabricated by multiple nitrogen ion-implantations (3 times for sample A and 4 times for sample B) into a p-type 4H-SiC epitaxial layer. The implantation depth profiles are calculated by using the Monte Carlo simulator TRIM. The fabrication process and the I-V and C V characteristics of the lateral Ti/4H-SiC Schottky barrier diodes (SBDs) fabricated on these multiple box-like ion-implantation layers are presented in detail. Measurements of the reverse I V characteristics demonstrate a low reverse current, which is good enough for many SiC-based devices such as SiC metal-semiconductor field-effect transistors (MESFETs), and SiC static induction transistors (SITs). The parameters of the diodes are extracted from the forward I-V and C-V characteristics. The values of ideality factor n of SBDs for samples A and B are 3.0 and 3.5 respectively, and the values of series resistance Rs are 11.9 and 1.0 kf~ respectively. The values of barrier height φB of Ti/4H-SiC are 0.95 and 0.72 eV obtained by the I-V method and 1.14 and 0.93 eV obtained by the C-V method for samples A and B respectively. The activation rates for the implanted nitrogen ions of samples A and B are 2% and 4% respectively extracted from C V testing results.展开更多
In order to reduce deep level defects, the theory and process design of 4H-SiC homoepitaxial layer implanted by carbon ion are studied. With the Monte Carlo simulator TRIM, the ion implantation range, location of peak...In order to reduce deep level defects, the theory and process design of 4H-SiC homoepitaxial layer implanted by carbon ion are studied. With the Monte Carlo simulator TRIM, the ion implantation range, location of peak concentration and longitudinal straggling of carbon are calculated. The process for improving deep energy level in undoped 4H-SiC homoepitaxial layer by three times carbon ion-implantation is proposed, including implantation energy, dose, the SiO2 resist mask, annealing temperature, annealing time and annealing protection. The deep energy level in 4H-SiC material can be significantly improved by implantation of carbon atoms into a shallow surface layer. The damage of crystal lattice can be repaired well, and the carbon ions are effectively activated after 1 600 ℃ annealing, meanwhile, deep level defects are decreased.展开更多
A straight magnetic filtering arc source is used to deposit thin films of titanium nitride. The properties of the films depend strongly on the deposition process. TiN films can be deposited directly onto heated substr...A straight magnetic filtering arc source is used to deposit thin films of titanium nitride. The properties of the films depend strongly on the deposition process. TiN films can be deposited directly onto heated substrates in a nitrogen atmosphere or onto unbiased substrates by condensing the Ti^+ ion beam in about 300 eV N2^+ nitrogen ion bombardment. In the latter case, the film stoichiometry is varied from an N:Ti ratio of 0.6-1.1 by controlling the arrival rates of Ti and nitrogen ions. Meanwhile, simple models are used to describe the evolution of compressive stress as function of the arrival ratio and the composition of the ion-assisted TiN films.展开更多
The sharp luminescent peaks in Yb and Er-implanted InP,SI-InP,GaAs,and n-GaAs were observed at 77K.The peaks at 1.0 and 1.5μm come from(4f)~2F_(5/2)→~2F_(7/2)of Yb^(3+)and ~4I_(13/2)→~4I_(15/2)of Er^(3+), respectiv...The sharp luminescent peaks in Yb and Er-implanted InP,SI-InP,GaAs,and n-GaAs were observed at 77K.The peaks at 1.0 and 1.5μm come from(4f)~2F_(5/2)→~2F_(7/2)of Yb^(3+)and ~4I_(13/2)→~4I_(15/2)of Er^(3+), respectively.The optimum luminescent intensities can be obtained from Yb-implanted and Er-implanted sam- ples which were annealed at 800 and 750℃,respectively.A ccording to the analyses of PL and the rocking curve of X-ray double crystal diffraction,the best crystal structure of implanted InP layer has been obtained by an- nealing at 850℃.The interaction between Yb^(3+)and Er^(3+)in the SI-InP has been investigated for the first time. The quenching effect of Yb^(3+)and Er^(3+)with each other has been observed when the doses of Yb and Er-im- planted SI-InP are equal.展开更多
Isothermal and cyclic oxidation behaviors of pure and yttrium-implanted nickel were studied at 1 000℃ in air. The oxide scales formed on nickel substrates were performed using SEM and TEM. It was found that Y-implant...Isothermal and cyclic oxidation behaviors of pure and yttrium-implanted nickel were studied at 1 000℃ in air. The oxide scales formed on nickel substrates were performed using SEM and TEM. It was found that Y-implantation greatly improved the anti-oxidation ability of nickel both in isothermal and cyclic oxidizing experiments. Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium. The main reason for the improvement in anti-oxidation and adhesion of oxide scale was Y-implantation greatly reduced the grain size of NiO and lowered the compressive stress within the scale. Yttrium implantation enhanced the adhesion of protective NiO oxide scale formed on nickel substrate.展开更多
Single GaAs/Al0.5Ga0.5As V-grooved quantum wire modified by selective ion-implantation and rapid thermally annealing was investigated by spatially-resolved microphotoluminescence and magneto-resistance measurement. Sp...Single GaAs/Al0.5Ga0.5As V-grooved quantum wire modified by selective ion-implantation and rapid thermally annealing was investigated by spatially-resolved microphotoluminescence and magneto-resistance measurement. Spatially-resolved photoluminescence results indicate that the ion-implantation induced quantum well intermixing raises significantly the electron subband energies of the side quantum wells and vertical quantum wells, and more efficient accumulation of electrons in the quantum wires is achieved. Furthermore, the polarization properties of the photoluminescence from the quantum wires show large linear polarization degree up to 63%. Magneto- transport investigation on the ion implanted quantum wire samples presents the quasi-one dimensional intrinsic motion of electrons, which is important for the design and optimization of one dimensional electronic devices.展开更多
I. INTRODUCTIONIon-implantation technique is a new technique developed in recent years. It was first applied to semiconductor devices in the 1960s, and then widespread into many fields such as solid state physics and ...I. INTRODUCTIONIon-implantation technique is a new technique developed in recent years. It was first applied to semiconductor devices in the 1960s, and then widespread into many fields such as solid state physics and material science. However, only a展开更多
基金National Natural Science Foundation of China(No.29231011)National Natural Science Foundation of Colombia(No.M018327)
文摘Isothermal and cyclic oxidation behaviours of pure and yttrium-implanted nickel were studied at 1000℃ in air. Scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM) were used to examine the micro-morphology and structure of oxide scales formed on the nickel substrate. It was found that Y-implantation significantly improved the anti- oxidation ability of nickel in both isothermal and cyclic oxidizing experiments. Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium. The main reason for the improvement in anti-oxidation of nickel was that Y- implantation greatly reduced the growing speed and grain size of NiO. This fine-grained NiO oxide film might have better high temperature plasticity and could relieve parts of compressive stress by means of creeping, and maintained a ridge character and a relatively low internal stress level. Hence yttrium ion-implantation remarkably enhanced the adhesion of protective NiO oxide scale formed on the nickel substrate.
基金Natural Science Foundation of JX Province (0650035)
文摘Silver foils and ion-implanted silver foils exposed to atomic oxygen (AO) generated in a ground simulation facility were investigated by the quartz crystal microbalance (QCM), the scanning electron microscopy (SEM) and the X-ray photoelectron spectroscopy (XPS). The experimental results show the presence of Ag2O and AgO in an oxidation process of the silver foil having exposure to AO. As soon as silver comes under the bombardment of atomic oxygen, the oxidation process starts with a thick film forming on the silver surface. Because of the development of stresses, the oxide layer gets cracked and spalled, which leads to appearance of a new silver surface intensifying further oxidation. At last, AgO begins to form on the outer surface of the oxide film. The analytical results of the XPS and the AES attest to formation of a continuous high-quality protective oxide-based layer on the surface of ion-implanted silver films after exposure to AO. This layer can well protect materials in question from erosion.
文摘From the theoretical analysis of the thermionic emission model of current-voltage characteristics, this paper extracts the parameters for the gate Schottky contact of two ion-implanted 4H-SiC metal-semiconductor field-effect transistors (sample A and sample B for three and four times multiple ion-implantation channel region respectively) fabricated in the experiment, including the ideality factor, the series resistance, the zero-field barrier height, the interface oxide capacitance, the interface state density distribution, the neutral level of interface states and the fixed space charge density. The methods to improve the interface of the ion-implanted Schottky contact are given at last.
文摘Ion-implantation layers are fabricated by multiple nitrogen ion-implantations (3 times for sample A and 4 times for sample B) into a p-type 4H-SiC epitaxial layer. The implantation depth profiles are calculated by using the Monte Carlo simulator TRIM. The fabrication process and the I-V and C V characteristics of the lateral Ti/4H-SiC Schottky barrier diodes (SBDs) fabricated on these multiple box-like ion-implantation layers are presented in detail. Measurements of the reverse I V characteristics demonstrate a low reverse current, which is good enough for many SiC-based devices such as SiC metal-semiconductor field-effect transistors (MESFETs), and SiC static induction transistors (SITs). The parameters of the diodes are extracted from the forward I-V and C-V characteristics. The values of ideality factor n of SBDs for samples A and B are 3.0 and 3.5 respectively, and the values of series resistance Rs are 11.9 and 1.0 kf~ respectively. The values of barrier height φB of Ti/4H-SiC are 0.95 and 0.72 eV obtained by the I-V method and 1.14 and 0.93 eV obtained by the C-V method for samples A and B respectively. The activation rates for the implanted nitrogen ions of samples A and B are 2% and 4% respectively extracted from C V testing results.
基金Supported by the National Natural Science Foundation of China (No. 61006008)Xi'an Applied Materials Innovation Fund (No. XA-AM-200607)
文摘In order to reduce deep level defects, the theory and process design of 4H-SiC homoepitaxial layer implanted by carbon ion are studied. With the Monte Carlo simulator TRIM, the ion implantation range, location of peak concentration and longitudinal straggling of carbon are calculated. The process for improving deep energy level in undoped 4H-SiC homoepitaxial layer by three times carbon ion-implantation is proposed, including implantation energy, dose, the SiO2 resist mask, annealing temperature, annealing time and annealing protection. The deep energy level in 4H-SiC material can be significantly improved by implantation of carbon atoms into a shallow surface layer. The damage of crystal lattice can be repaired well, and the carbon ions are effectively activated after 1 600 ℃ annealing, meanwhile, deep level defects are decreased.
文摘A straight magnetic filtering arc source is used to deposit thin films of titanium nitride. The properties of the films depend strongly on the deposition process. TiN films can be deposited directly onto heated substrates in a nitrogen atmosphere or onto unbiased substrates by condensing the Ti^+ ion beam in about 300 eV N2^+ nitrogen ion bombardment. In the latter case, the film stoichiometry is varied from an N:Ti ratio of 0.6-1.1 by controlling the arrival rates of Ti and nitrogen ions. Meanwhile, simple models are used to describe the evolution of compressive stress as function of the arrival ratio and the composition of the ion-assisted TiN films.
基金Project supported by the National Natural Science Foundation of China
文摘The sharp luminescent peaks in Yb and Er-implanted InP,SI-InP,GaAs,and n-GaAs were observed at 77K.The peaks at 1.0 and 1.5μm come from(4f)~2F_(5/2)→~2F_(7/2)of Yb^(3+)and ~4I_(13/2)→~4I_(15/2)of Er^(3+), respectively.The optimum luminescent intensities can be obtained from Yb-implanted and Er-implanted sam- ples which were annealed at 800 and 750℃,respectively.A ccording to the analyses of PL and the rocking curve of X-ray double crystal diffraction,the best crystal structure of implanted InP layer has been obtained by an- nealing at 850℃.The interaction between Yb^(3+)and Er^(3+)in the SI-InP has been investigated for the first time. The quenching effect of Yb^(3+)and Er^(3+)with each other has been observed when the doses of Yb and Er-im- planted SI-InP are equal.
文摘Isothermal and cyclic oxidation behaviors of pure and yttrium-implanted nickel were studied at 1 000℃ in air. The oxide scales formed on nickel substrates were performed using SEM and TEM. It was found that Y-implantation greatly improved the anti-oxidation ability of nickel both in isothermal and cyclic oxidizing experiments. Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium. The main reason for the improvement in anti-oxidation and adhesion of oxide scale was Y-implantation greatly reduced the grain size of NiO and lowered the compressive stress within the scale. Yttrium implantation enhanced the adhesion of protective NiO oxide scale formed on nickel substrate.
基金supported by the National Natural Science Foundation of China(Grant Nos.10374018 and 10321003)the Scientific Committee of Shanghai(Grant No.03DJ14001)
文摘Single GaAs/Al0.5Ga0.5As V-grooved quantum wire modified by selective ion-implantation and rapid thermally annealing was investigated by spatially-resolved microphotoluminescence and magneto-resistance measurement. Spatially-resolved photoluminescence results indicate that the ion-implantation induced quantum well intermixing raises significantly the electron subband energies of the side quantum wells and vertical quantum wells, and more efficient accumulation of electrons in the quantum wires is achieved. Furthermore, the polarization properties of the photoluminescence from the quantum wires show large linear polarization degree up to 63%. Magneto- transport investigation on the ion implanted quantum wire samples presents the quasi-one dimensional intrinsic motion of electrons, which is important for the design and optimization of one dimensional electronic devices.
基金Project supported by the National Natural Science Foundation of China.
文摘I. INTRODUCTIONIon-implantation technique is a new technique developed in recent years. It was first applied to semiconductor devices in the 1960s, and then widespread into many fields such as solid state physics and material science. However, only a