Si based single electron transistor (SET) is fabricated successfully on p type SIMOX substrate,based on electron beam (EB) lithography,reactive ion etching (RIE) and thermal oxidation.In particular,using thermal oxi...Si based single electron transistor (SET) is fabricated successfully on p type SIMOX substrate,based on electron beam (EB) lithography,reactive ion etching (RIE) and thermal oxidation.In particular,using thermal oxidation and etching off the oxide layer,a one dimensional Si quantum wire can be converted into several quantum dots inside quantum wire in connection with the source and drain regions.The differential conductance (d I ds /d V ds ) oscillations and the Coulomb staircases in the source drain current ( I ds ) are shown clearly dependent on the source drain voltage at 5 3K.The I ds V gs (gate voltage) oscillations are observed from the I ds V gs characteristics as a function of V gs at different temperatures and various values of V ds .For a SET whose total capacitance is about 9 16aF,the I ds V gs oscillations can be observed at 77K.展开更多
Based on the fluid network theory,the possibility of utilizing regenerator flow resistance to suppress the direct current （DC） flow induced by the introduction of a double-inlet in a pulse tube cooler is investigate...Based on the fluid network theory,the possibility of utilizing regenerator flow resistance to suppress the direct current （DC） flow induced by the introduction of a double-inlet in a pulse tube cooler is investigated theoretically. The calculation results show that increasing regenerator flow resistance can lead to a smaller extent of DC flow.Therefore,a better stability performance of the cooler can be realized.On this basis,the stability characteristics of the cooler with various regenerator matrix arrangements are studied by experiments.By replacing 30% space of 247 screens of stainless steel mesh at the cold part of the regenerator by lead balls of 0.25 mm diameter,a long-time stable temperature output at 80 K region is achieved. This achievement provides a new way to obtain stable performance for pulse tube coolers at high temperature and is helpful for its application.展开更多
The on-resistance degradations of the p-type lateral extended drain MOS transistor （pLEDMOS） with thick gate oxide under different hot carrier stress conditions are different, which has been experimentally investiga...The on-resistance degradations of the p-type lateral extended drain MOS transistor （pLEDMOS） with thick gate oxide under different hot carrier stress conditions are different, which has been experimentally investigated. This difference results from the interface trap generation and the hot electron injection, and trapping into the thick gate oxide and field oxide of the pLEDMOS transistor. An improved method to reduce the on-resistance degradations is also presented, which uses the field oxide as the gate oxide instead of the thick gate oxide. The effects are analyzed with a MEDICI simulator.展开更多
A novel structure of ideal ohmic contact p^＋ （SiGeC）-n^- -n^＋ diodes with three-step graded doping concentration in the base region is presented, and the changing doping concentration gradient is also optimized. U...A novel structure of ideal ohmic contact p^＋ （SiGeC）-n^- -n^＋ diodes with three-step graded doping concentration in the base region is presented, and the changing doping concentration gradient is also optimized. Using MEDICI, the physical parameter models applicable for SiGeC/Si heterojunction power diodes are given. The simulation results indicate that the diodes with graded doping concentration in the base region not only have the merit of fast and soft reverse recovery but also double reverse blocking voltage,and their forward conducting voltage has dropped to some extent,compared to the diodes with constant doping concentration in the base region. The new structure achieves a good trade-off in Qs-Vf-Ir ,and its combination of properties is superior to ideal ohmic contact diodes and conventional diodes.展开更多
Objective To study the techniques and clinical applications of intra-vascular stenting in the treatment of superior vana cava obliteration syndrome (SVS). Methods In 9 cases of SVS, primary lesions were all confirme...Objective To study the techniques and clinical applications of intra-vascular stenting in the treatment of superior vana cava obliteration syndrome (SVS). Methods In 9 cases of SVS, primary lesions were all confirmed as malignancy (primary pulmonary carcinoma of right upper lobe) histolo-pathologically. By route of right femoral vein, SVS catheterization and DSA was made. The length of the strictures and the diameters of normal superior vana cavae (SVC) were measured for the choice of appropriate stents. The option of stemt diameter is 10% larger than that of normal SVCs. The upper and lower ends of the stent should be 1–2 cm protruding from the ends of the stricture. The stent was dilated with a balloon after its successful placement. Therapy of original lesions was continued together with anticoagulant. Stents were observed about their positions by fluoroscopy or chest films, and about patency of SVC by Doppler. Results After the placement of a stent, DSA revealed the contrast media in the SVCs passed along smoothly, diameters of SVCs almost normal, collateral branches diminished remarkably. Average SVC pressure was decreased from 26.4 cmH2O before the placement down to 15.7 cmH2O, with an obvious difference (P<0.01= by statistics. Related clinical symptoms and signs disappeared or relieved. Subsidised were swelling of head and neck, upper extremities and chest. Excretion of urine increased. Gorgeous superficial veins in the chest could not be detected any more. Conclusion The therapy of intra-vascular stenting to treat SVS is microinvasive, simple and effective. Key words superior vana cava syndrome - tumor - stent - image diagnosis - interventional therapy展开更多
Based on the surface-gate and buried-gate structures,a novel buried-gate structure called the planar type buried-gate (PTBG) structure for static induction devices (SIDs) is proposed.An approach to realize a buried-ga...Based on the surface-gate and buried-gate structures,a novel buried-gate structure called the planar type buried-gate (PTBG) structure for static induction devices (SIDs) is proposed.An approach to realize a buried-gate type static induction transistor by conventional planar process technology is presented.Using this structure,it is successfully avoided the second epitaxy with a high degree of difficulty and the complicated mesa process in conventional buried gate.The experimental results demonstrate that this structure is desirable for application in power SIDs.Its advantages are high breakdown voltage and blocking gain.展开更多
文摘Si based single electron transistor (SET) is fabricated successfully on p type SIMOX substrate,based on electron beam (EB) lithography,reactive ion etching (RIE) and thermal oxidation.In particular,using thermal oxidation and etching off the oxide layer,a one dimensional Si quantum wire can be converted into several quantum dots inside quantum wire in connection with the source and drain regions.The differential conductance (d I ds /d V ds ) oscillations and the Coulomb staircases in the source drain current ( I ds ) are shown clearly dependent on the source drain voltage at 5 3K.The I ds V gs (gate voltage) oscillations are observed from the I ds V gs characteristics as a function of V gs at different temperatures and various values of V ds .For a SET whose total capacitance is about 9 16aF,the I ds V gs oscillations can be observed at 77K.
基金The National Natural Science Foundation of China(No.50406009).
文摘Based on the fluid network theory,the possibility of utilizing regenerator flow resistance to suppress the direct current （DC） flow induced by the introduction of a double-inlet in a pulse tube cooler is investigated theoretically. The calculation results show that increasing regenerator flow resistance can lead to a smaller extent of DC flow.Therefore,a better stability performance of the cooler can be realized.On this basis,the stability characteristics of the cooler with various regenerator matrix arrangements are studied by experiments.By replacing 30% space of 247 screens of stainless steel mesh at the cold part of the regenerator by lead balls of 0.25 mm diameter,a long-time stable temperature output at 80 K region is achieved. This achievement provides a new way to obtain stable performance for pulse tube coolers at high temperature and is helpful for its application.
文摘The on-resistance degradations of the p-type lateral extended drain MOS transistor （pLEDMOS） with thick gate oxide under different hot carrier stress conditions are different, which has been experimentally investigated. This difference results from the interface trap generation and the hot electron injection, and trapping into the thick gate oxide and field oxide of the pLEDMOS transistor. An improved method to reduce the on-resistance degradations is also presented, which uses the field oxide as the gate oxide instead of the thick gate oxide. The effects are analyzed with a MEDICI simulator.
文摘A novel structure of ideal ohmic contact p^＋ （SiGeC）-n^- -n^＋ diodes with three-step graded doping concentration in the base region is presented, and the changing doping concentration gradient is also optimized. Using MEDICI, the physical parameter models applicable for SiGeC/Si heterojunction power diodes are given. The simulation results indicate that the diodes with graded doping concentration in the base region not only have the merit of fast and soft reverse recovery but also double reverse blocking voltage,and their forward conducting voltage has dropped to some extent,compared to the diodes with constant doping concentration in the base region. The new structure achieves a good trade-off in Qs-Vf-Ir ,and its combination of properties is superior to ideal ohmic contact diodes and conventional diodes.
文摘Objective To study the techniques and clinical applications of intra-vascular stenting in the treatment of superior vana cava obliteration syndrome (SVS). Methods In 9 cases of SVS, primary lesions were all confirmed as malignancy (primary pulmonary carcinoma of right upper lobe) histolo-pathologically. By route of right femoral vein, SVS catheterization and DSA was made. The length of the strictures and the diameters of normal superior vana cavae (SVC) were measured for the choice of appropriate stents. The option of stemt diameter is 10% larger than that of normal SVCs. The upper and lower ends of the stent should be 1–2 cm protruding from the ends of the stricture. The stent was dilated with a balloon after its successful placement. Therapy of original lesions was continued together with anticoagulant. Stents were observed about their positions by fluoroscopy or chest films, and about patency of SVC by Doppler. Results After the placement of a stent, DSA revealed the contrast media in the SVCs passed along smoothly, diameters of SVCs almost normal, collateral branches diminished remarkably. Average SVC pressure was decreased from 26.4 cmH2O before the placement down to 15.7 cmH2O, with an obvious difference (P<0.01= by statistics. Related clinical symptoms and signs disappeared or relieved. Subsidised were swelling of head and neck, upper extremities and chest. Excretion of urine increased. Gorgeous superficial veins in the chest could not be detected any more. Conclusion The therapy of intra-vascular stenting to treat SVS is microinvasive, simple and effective. Key words superior vana cava syndrome - tumor - stent - image diagnosis - interventional therapy
文摘Based on the surface-gate and buried-gate structures,a novel buried-gate structure called the planar type buried-gate (PTBG) structure for static induction devices (SIDs) is proposed.An approach to realize a buried-gate type static induction transistor by conventional planar process technology is presented.Using this structure,it is successfully avoided the second epitaxy with a high degree of difficulty and the complicated mesa process in conventional buried gate.The experimental results demonstrate that this structure is desirable for application in power SIDs.Its advantages are high breakdown voltage and blocking gain.
