The mode coupling is a major factor to affect the precision of the micro electromechanical systems（MEMS） gyroscope. Currently, many MEMS gyroscopes with separate oscillation modes for drive and detection have been d...The mode coupling is a major factor to affect the precision of the micro electromechanical systems（MEMS） gyroscope. Currently, many MEMS gyroscopes with separate oscillation modes for drive and detection have been developed to decrease the mode coupling, but the gyroscope accuracy can not satisfy the high-precision demand well. Therefore, high performance decoupled MEMS gyroscopes is still a hot topic at present. An innovative design scheme for a MEMS gyroscope is designed, and in this design, the inertial mass is divided into three parts including the inner mass, the outer mass and the main frame mass. The masses are supported and separated by a set of mutually orthogonal beams to decouple their movements. Moreover, the design is modelled by multi-port-element network（MuPEN） method and the simulation results show that the mode coupling of the gyroscope between driving and sensing mode was eliminated effectively. Furthermore, we proposed a new silicon-on-insulator（SOI） process to fabricate the gyroscope. The scale factor of the fabricated gyroscope is 8.9 mV/（（~）os） and the quality factor（Q-factor） is as high as 600 at atmosphere pressure, and then, the resonant frequency, scale factor and bias drift has been test. Process and test results show that the proposed MEMS gyroscope are effective for decrease mode coupling, furthermore, it can achieve a high performance at atmosphere pressure. Furthermore, the MEMS gyroscope can achieve a high performance at atmosphere pressure. The research can be taken as good advice for the design and fabrication of MEMS gyroscope, meanwhile, it also provides technical support for speeding up of MEMS gyroscope industrialization.展开更多
A betavohaic Microbattery was studied. The diode was composed of a PIN structure with an active area of 10 mm × 10 mm to collect the charge from a 10mCi Ni-63 source. An open circuit voltage of 0. 16 V and a shor...A betavohaic Microbattery was studied. The diode was composed of a PIN structure with an active area of 10 mm × 10 mm to collect the charge from a 10mCi Ni-63 source. An open circuit voltage of 0. 16 V and a short circuit current density of 67.6 nA/cm2 were measured. An efficiency （η） of 1.44% was obtained. The performance of device was limited by high series resistance, edge recombination and attenuation of electron in PIN diodes. It is expected to be improved by optimizing the design and using more suitable radioisotope.展开更多
This paper reports that the nickel silicide ohmic contacts to n-type 6H-SiC have been fabricated. Transfer length method test patterns with NiSi/SiC and NiSi2/SiC structure axe formed on N-wells created by N^＋ ion im...This paper reports that the nickel silicide ohmic contacts to n-type 6H-SiC have been fabricated. Transfer length method test patterns with NiSi/SiC and NiSi2/SiC structure axe formed on N-wells created by N^＋ ion implantation into Si-faced p-type 6H-SiC epilayer respectively. NiSi and NiSi2 films are prepared by annealing the Ni and Si films separately deposited. A two-step annealing technology is performed for decreasing of oxidation problems occurred during high temperature processes. The specific contact resistance Pc of NiSi contact to n-type 6H-SiC as low as 1.78× 10^-6Ωcm^2 is achieved after a two-step annealing at 350 ℃for 20 min and 950℃ for 3 min in N2. And 3.84×10-6Ωcm^2 for NiSi2 contact is achieved. The result for sheet resistance Rsh of the N＋ implanted layers is about 1210Ω/□. X-ray diffraction analysis shows the formation of nickel silicide phases at the metal/n-SiC interface after thermal annealing. The surfaces of the nickel silicide after thermal annealing are analysed by scanning electron microscope.展开更多
A 4H SiC betavoltaic nuclear battery is demonstrated. A Schottky barrier diode is utilized for carrier separation. Under illumination of Ni-63 source with an apparent activity of 4mCi/cm^2, an open circuit voltage of ...A 4H SiC betavoltaic nuclear battery is demonstrated. A Schottky barrier diode is utilized for carrier separation. Under illumination of Ni-63 source with an apparent activity of 4mCi/cm^2, an open circuit voltage of 0.49 V and a short circuit current density of 29.44nA/cm^2 are measured. A power conversion efficiency of 1.2% is obtained. The performance of the device is limited by low shunt resistance, backscattering and attenuation of electron energy in air and Schottky electrode. It is expected to be significantly improved by optimizing the design and processing technology of the device.展开更多
By formation of an intermediate semiconductor layer （ISL） with a narrow band gap at the metallic contact/SiC interface, this paper realises a new method to fabricate the low-resistance Ohmic contacts for SiC. An arr...By formation of an intermediate semiconductor layer （ISL） with a narrow band gap at the metallic contact/SiC interface, this paper realises a new method to fabricate the low-resistance Ohmic contacts for SiC. An array of transfer length method （TLM） test patterns is formed on N-wells created by P＋ ion implantation into Si-faced p-type 4H- SiC epilayer. The ISL of nickel-metal Ohmic contacts to n-type 4H-SiC could be formed by using Germanium ion implantation into SiC. The specific contact resistance pc as low as 4.23×10-5Ω·cm2 is achieved after annealing in N2 at 800 ℃ for 3 min, which is much lower than that （〉 900℃） in the typical SiC metallisation process. The sheet resistance Rsh of the implanted layers is 1.5 kΩ/□. The technique for converting photoresist into nanocrystalline graphite is used to protect the SiC surface in the annealing after Ge＋ ion implantations.展开更多
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2009AA04Z320)Xi’an Municipal Applied Materials Innovation Fund of China (Grant No. XA-AM-200801)
文摘The mode coupling is a major factor to affect the precision of the micro electromechanical systems（MEMS） gyroscope. Currently, many MEMS gyroscopes with separate oscillation modes for drive and detection have been developed to decrease the mode coupling, but the gyroscope accuracy can not satisfy the high-precision demand well. Therefore, high performance decoupled MEMS gyroscopes is still a hot topic at present. An innovative design scheme for a MEMS gyroscope is designed, and in this design, the inertial mass is divided into three parts including the inner mass, the outer mass and the main frame mass. The masses are supported and separated by a set of mutually orthogonal beams to decouple their movements. Moreover, the design is modelled by multi-port-element network（MuPEN） method and the simulation results show that the mode coupling of the gyroscope between driving and sensing mode was eliminated effectively. Furthermore, we proposed a new silicon-on-insulator（SOI） process to fabricate the gyroscope. The scale factor of the fabricated gyroscope is 8.9 mV/（（~）os） and the quality factor（Q-factor） is as high as 600 at atmosphere pressure, and then, the resonant frequency, scale factor and bias drift has been test. Process and test results show that the proposed MEMS gyroscope are effective for decrease mode coupling, furthermore, it can achieve a high performance at atmosphere pressure. Furthermore, the MEMS gyroscope can achieve a high performance at atmosphere pressure. The research can be taken as good advice for the design and fabrication of MEMS gyroscope, meanwhile, it also provides technical support for speeding up of MEMS gyroscope industrialization.
基金Sponsored by the National High Technology Research and Development Program of China (863 Program,Grant No.2009AA04Z318)
文摘A betavohaic Microbattery was studied. The diode was composed of a PIN structure with an active area of 10 mm × 10 mm to collect the charge from a 10mCi Ni-63 source. An open circuit voltage of 0. 16 V and a short circuit current density of 67.6 nA/cm2 were measured. An efficiency （η） of 1.44% was obtained. The performance of device was limited by high series resistance, edge recombination and attenuation of electron in PIN diodes. It is expected to be improved by optimizing the design and using more suitable radioisotope.
基金Project supported by the National Basic Research Program of China （Grant No 2002CB311904）, the National Defense Basic Research Program of China （Grant No 51327010101） and the National Natural Science Foundation of China （Grant No 60376001）.
文摘This paper reports that the nickel silicide ohmic contacts to n-type 6H-SiC have been fabricated. Transfer length method test patterns with NiSi/SiC and NiSi2/SiC structure axe formed on N-wells created by N^＋ ion implantation into Si-faced p-type 6H-SiC epilayer respectively. NiSi and NiSi2 films are prepared by annealing the Ni and Si films separately deposited. A two-step annealing technology is performed for decreasing of oxidation problems occurred during high temperature processes. The specific contact resistance Pc of NiSi contact to n-type 6H-SiC as low as 1.78× 10^-6Ωcm^2 is achieved after a two-step annealing at 350 ℃for 20 min and 950℃ for 3 min in N2. And 3.84×10-6Ωcm^2 for NiSi2 contact is achieved. The result for sheet resistance Rsh of the N＋ implanted layers is about 1210Ω/□. X-ray diffraction analysis shows the formation of nickel silicide phases at the metal/n-SiC interface after thermal annealing. The surfaces of the nickel silicide after thermal annealing are analysed by scanning electron microscope.
基金supported by the National Natural Science Foundation of China (Grant No. 50775189) the Doctorate Foundation of Northwest-ern Polytechnical University (Grant No. CX200611)
文摘A 4H SiC betavoltaic nuclear battery is demonstrated. A Schottky barrier diode is utilized for carrier separation. Under illumination of Ni-63 source with an apparent activity of 4mCi/cm^2, an open circuit voltage of 0.49 V and a short circuit current density of 29.44nA/cm^2 are measured. A power conversion efficiency of 1.2% is obtained. The performance of the device is limited by low shunt resistance, backscattering and attenuation of electron energy in air and Schottky electrode. It is expected to be significantly improved by optimizing the design and processing technology of the device.
基金Project supported by the National Natural Science Foundation of China (Grant No J54508250120)Xi’an Applied Materials Innovation Fund (Grant No XA-AM-200704)
文摘By formation of an intermediate semiconductor layer （ISL） with a narrow band gap at the metallic contact/SiC interface, this paper realises a new method to fabricate the low-resistance Ohmic contacts for SiC. An array of transfer length method （TLM） test patterns is formed on N-wells created by P＋ ion implantation into Si-faced p-type 4H- SiC epilayer. The ISL of nickel-metal Ohmic contacts to n-type 4H-SiC could be formed by using Germanium ion implantation into SiC. The specific contact resistance pc as low as 4.23×10-5Ω·cm2 is achieved after annealing in N2 at 800 ℃ for 3 min, which is much lower than that （〉 900℃） in the typical SiC metallisation process. The sheet resistance Rsh of the implanted layers is 1.5 kΩ/□. The technique for converting photoresist into nanocrystalline graphite is used to protect the SiC surface in the annealing after Ge＋ ion implantations.
