There are some new results about photovoltaic transient response in the new effect. We suggest a theoretical model to explain the effect reasonably. The theoretical calculation results agree with that in experiments.
在应变异质结价带偏移从头算赝势法的理论计算中,建议一种以平均键能为参考能级的△E_v 值理论计算方法,该方法在以 Si 为衬底、以 Ge 为衬底和自由共度生长等3种不同应变情况的 Si/Ge 异质结价带偏移△E_v 值计算中,分别得到0.731eV、0...在应变异质结价带偏移从头算赝势法的理论计算中,建议一种以平均键能为参考能级的△E_v 值理论计算方法,该方法在以 Si 为衬底、以 Ge 为衬底和自由共度生长等3种不同应变情况的 Si/Ge 异质结价带偏移△E_v 值计算中,分别得到0.731eV、0.243eV 和0.521eV 的计算结果。展开更多
Lattice dynamics of strained(Si)_(4)/(Ge)_(4) superlattice grown pseudomorphically on (001)-oriented Si_(1-x)Ge_(x)(0≤x≤1)substrate is investigated.In the present calculations,the effects of strain and substrate are...Lattice dynamics of strained(Si)_(4)/(Ge)_(4) superlattice grown pseudomorphically on (001)-oriented Si_(1-x)Ge_(x)(0≤x≤1)substrate is investigated.In the present calculations,the effects of strain and substrate are discussed.展开更多
The effect of strains on the thermal conductivity of Si/Ge superlattices was investigated by nonequilibrium molecular dynamics（NEMD） simulation. The thermal conductivities experienced a near linear drop with increas...The effect of strains on the thermal conductivity of Si/Ge superlattices was investigated by nonequilibrium molecular dynamics（NEMD） simulation. The thermal conductivities experienced a near linear drop with increasing tensile and compressive strains. It was explained by the fact that the decrease of the phonons velocities and a mass of structural defects generated under strains. Meanwhile, a theoretical calculation based on Modified-Callaway model was performed,and it was found that the theoretical results were in good agreement with the molecular dynamics results.展开更多
Self-assembled Si/Ge quantum dot (QD) structures have been intensively studied in the last years for potential applications in Si based integrated optoelectronics [1]. For the demand of many technical applications, Ge...Self-assembled Si/Ge quantum dot (QD) structures have been intensively studied in the last years for potential applications in Si based integrated optoelectronics [1]. For the demand of many technical applications, Ge dot superlattices separated by Si can be deposited in order to increase the optical and electronic response. Raman scattering has proven to be an essential technique to characterize Si/Ge superlattices and Si/Ge dot superlattices [2,3,4]. However, most of Raman studies were concentrated on their optical modes of Si/Ge dot superlattices, but few of them were carried out to characterize the detail structural properties of Si/Ge dot superlattice structures. Here, Self-assembled Si/Ge dot multilayers with small, uncorrelated dots fabricated by molecular beam epitaxy in the Stranski-Krastanov growth mode are studied by Raman scattering of folded longitudinal acoustic (FLA) modes.展开更多
A series of Al-xSi-yGe filler metals(x=4–12 and y=10–40,wt%)were prepared,and the effect of Si and Ge on microstructure and melting characteristics of filler metals was studied.The thermodynamic model of Al-Si-Ge te...A series of Al-xSi-yGe filler metals(x=4–12 and y=10–40,wt%)were prepared,and the effect of Si and Ge on microstructure and melting characteristics of filler metals was studied.The thermodynamic model of Al-Si-Ge ternary alloy was established to analyze the phase formation mechanism of filler metals based on Miedema model,Tanaka model,and Toop equation.This research provided a basis for the composition optimization of filler metals and the analysis of metallurgical reaction process between filler metals and base materials.Results show that Al-Si-Ge alloy is composed of Al-Ge eutectic phase,Al-Si eutectic phase,and primary Si.Ge addition promotes the precipitation of primary Si.Ge is the main melting point depressant element of filler metals.With the increase in Ge content from 10wt%to 40wt%,the solid phase line of filler metals remains unchanged,whereas the liquidus temperature decreases from 567.65°C to 499.96°C.With the increase in Ge content of filler metal,Ge content in eutectic Si phase is increased,the endothermic peak of Al-Si eutectic reaction according to thermogravimetry curve becomes smoother,and Al-Si eutectic temperature is decreased.Ge addition can reduce the free energy of Al-Si alloy system.The lowest point of free energy is located on Al-Ge side.The eutectic Ge phase with the composition similar to pure Ge composition is the most likely to appear in the microstructure of filler metals,whereas the eutectic Si phase with the composition similar to pure Si composition is the least likely to appear.The thermodynamic calculation results are consistent with the experiment results.展开更多
文摘There are some new results about photovoltaic transient response in the new effect. We suggest a theoretical model to explain the effect reasonably. The theoretical calculation results agree with that in experiments.
文摘Lattice dynamics of strained(Si)_(4)/(Ge)_(4) superlattice grown pseudomorphically on (001)-oriented Si_(1-x)Ge_(x)(0≤x≤1)substrate is investigated.In the present calculations,the effects of strain and substrate are discussed.
基金Supported by the National Natural Science Foundation of China(No.51706039)
文摘The effect of strains on the thermal conductivity of Si/Ge superlattices was investigated by nonequilibrium molecular dynamics（NEMD） simulation. The thermal conductivities experienced a near linear drop with increasing tensile and compressive strains. It was explained by the fact that the decrease of the phonons velocities and a mass of structural defects generated under strains. Meanwhile, a theoretical calculation based on Modified-Callaway model was performed,and it was found that the theoretical results were in good agreement with the molecular dynamics results.
文摘Self-assembled Si/Ge quantum dot (QD) structures have been intensively studied in the last years for potential applications in Si based integrated optoelectronics [1]. For the demand of many technical applications, Ge dot superlattices separated by Si can be deposited in order to increase the optical and electronic response. Raman scattering has proven to be an essential technique to characterize Si/Ge superlattices and Si/Ge dot superlattices [2,3,4]. However, most of Raman studies were concentrated on their optical modes of Si/Ge dot superlattices, but few of them were carried out to characterize the detail structural properties of Si/Ge dot superlattice structures. Here, Self-assembled Si/Ge dot multilayers with small, uncorrelated dots fabricated by molecular beam epitaxy in the Stranski-Krastanov growth mode are studied by Raman scattering of folded longitudinal acoustic (FLA) modes.
基金National Natural Science Foundation of China(U22A20191)。
文摘A series of Al-xSi-yGe filler metals(x=4–12 and y=10–40,wt%)were prepared,and the effect of Si and Ge on microstructure and melting characteristics of filler metals was studied.The thermodynamic model of Al-Si-Ge ternary alloy was established to analyze the phase formation mechanism of filler metals based on Miedema model,Tanaka model,and Toop equation.This research provided a basis for the composition optimization of filler metals and the analysis of metallurgical reaction process between filler metals and base materials.Results show that Al-Si-Ge alloy is composed of Al-Ge eutectic phase,Al-Si eutectic phase,and primary Si.Ge addition promotes the precipitation of primary Si.Ge is the main melting point depressant element of filler metals.With the increase in Ge content from 10wt%to 40wt%,the solid phase line of filler metals remains unchanged,whereas the liquidus temperature decreases from 567.65°C to 499.96°C.With the increase in Ge content of filler metal,Ge content in eutectic Si phase is increased,the endothermic peak of Al-Si eutectic reaction according to thermogravimetry curve becomes smoother,and Al-Si eutectic temperature is decreased.Ge addition can reduce the free energy of Al-Si alloy system.The lowest point of free energy is located on Al-Ge side.The eutectic Ge phase with the composition similar to pure Ge composition is the most likely to appear in the microstructure of filler metals,whereas the eutectic Si phase with the composition similar to pure Si composition is the least likely to appear.The thermodynamic calculation results are consistent with the experiment results.
