The motion of current filaments in avalanching PIN diodes has been investigated in this paper by 2D transient numerical simulations. The simulation results show that the filament can move along the length of the PIN d...The motion of current filaments in avalanching PIN diodes has been investigated in this paper by 2D transient numerical simulations. The simulation results show that the filament can move along the length of the PIN diode back and forth when the self-heating effect is considered. The voltage waveform varies periodically due to the motion of the filament. The filament motion is driven by the temperature gradient in the filament due to the negative temperature dependence of the impact ionization rates. Contrary to the traditional understanding that current filamentation is a potential cause of thermal destruction, it is shown in this paper that the thermally-driven motion of current filaments leads to the homogenization of temperature in the diode and is expected to have a positive influence on the failure threshold of the PIN diode.展开更多
Metal organic chemical vapor deposition(MOCVD) is a key equipment in the manufacturing of semiconductor optoelectronic devices and microwave devices in industry. Heating system is a vital part of MOCVD. Specific heati...Metal organic chemical vapor deposition(MOCVD) is a key equipment in the manufacturing of semiconductor optoelectronic devices and microwave devices in industry. Heating system is a vital part of MOCVD. Specific heating device and thermal control technology are needed for each new reactor design. By using resistance-wire heating MOCVD reaction chamber model, thermal analysis and structure optimization of the reactor were developed from the vertical position and the distance between coils of the resistance-wire heater. It is indicated that, within a certain range, the average temperature of the graphite susceptor varies linearly with the vertical distance of heater to susceptor, and with the changed distances between the coils; furthermore, single resistance-wire heater should be placed loosely in the internal and tightly in the external. The modulate accuracy of the temperature field approximately equals the change of the average temperature corresponding to the change of the coil position.展开更多
为了进一步提高电子束流发生系统工作的可靠性和稳定性,提高电子束加工质量,采用AC-DC-AC-DC-AC-DC的拓扑电路、新型功率变压器、高压脉冲检测技术、优化的束流反馈控制与灯丝加热电流闭环反馈控制技术等,分别优化了高压加速电源、偏压...为了进一步提高电子束流发生系统工作的可靠性和稳定性,提高电子束加工质量,采用AC-DC-AC-DC-AC-DC的拓扑电路、新型功率变压器、高压脉冲检测技术、优化的束流反馈控制与灯丝加热电流闭环反馈控制技术等,分别优化了高压加速电源、偏压电源与灯丝加热电源。将所研制逆变电源与150 k V/30 k W电子枪、真空系统等组成了一套电子束流发生系统,测试了该电子束流发生系统输出的高压、最大束流以及灯丝加热电流、偏压变化对束流输出的影响。试验结果表明:经过优化的逆变电源高压输出达到-150 k V,高压输出线性度较好,最大束流达到200 m A;高压、灯丝加热电流给定时,随着偏压降低,束流输出逐渐增大;高压、偏压给定时,随着灯丝加热电流增大,束流输出存在死区、线性增大区和恒流区。展开更多
基金Project supported by the National Natural Science Foundation of China(No.60776034)
文摘The motion of current filaments in avalanching PIN diodes has been investigated in this paper by 2D transient numerical simulations. The simulation results show that the filament can move along the length of the PIN diode back and forth when the self-heating effect is considered. The voltage waveform varies periodically due to the motion of the filament. The filament motion is driven by the temperature gradient in the filament due to the negative temperature dependence of the impact ionization rates. Contrary to the traditional understanding that current filamentation is a potential cause of thermal destruction, it is shown in this paper that the thermally-driven motion of current filaments leads to the homogenization of temperature in the diode and is expected to have a positive influence on the failure threshold of the PIN diode.
基金Projects(61376076,61274026,61377024)supported by the National Natural Science Foundation of ChinaProjects(12C0108,13C321)supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProjects(2013FJ2011,2013FJ4232)supported by the Science and Technology Plan of Hunan Province,China
文摘Metal organic chemical vapor deposition(MOCVD) is a key equipment in the manufacturing of semiconductor optoelectronic devices and microwave devices in industry. Heating system is a vital part of MOCVD. Specific heating device and thermal control technology are needed for each new reactor design. By using resistance-wire heating MOCVD reaction chamber model, thermal analysis and structure optimization of the reactor were developed from the vertical position and the distance between coils of the resistance-wire heater. It is indicated that, within a certain range, the average temperature of the graphite susceptor varies linearly with the vertical distance of heater to susceptor, and with the changed distances between the coils; furthermore, single resistance-wire heater should be placed loosely in the internal and tightly in the external. The modulate accuracy of the temperature field approximately equals the change of the average temperature corresponding to the change of the coil position.
文摘为了进一步提高电子束流发生系统工作的可靠性和稳定性,提高电子束加工质量,采用AC-DC-AC-DC-AC-DC的拓扑电路、新型功率变压器、高压脉冲检测技术、优化的束流反馈控制与灯丝加热电流闭环反馈控制技术等,分别优化了高压加速电源、偏压电源与灯丝加热电源。将所研制逆变电源与150 k V/30 k W电子枪、真空系统等组成了一套电子束流发生系统,测试了该电子束流发生系统输出的高压、最大束流以及灯丝加热电流、偏压变化对束流输出的影响。试验结果表明:经过优化的逆变电源高压输出达到-150 k V,高压输出线性度较好,最大束流达到200 m A;高压、灯丝加热电流给定时,随着偏压降低,束流输出逐渐增大;高压、偏压给定时,随着灯丝加热电流增大,束流输出存在死区、线性增大区和恒流区。
