为了准确地表征4H-SiC MOSFET经过高温栅偏(HTGB)测试后的栅源电压漂移,优化氮退火工艺条件以改善MOSFET栅源电压的稳定性,在n型4H-SiC(0001)外延片上制备了横向扩散MOSFET(LDMOSFET)和纵向扩散MOSFET(VDMOSFET)。对栅氧化层采用不同温...为了准确地表征4H-SiC MOSFET经过高温栅偏(HTGB)测试后的栅源电压漂移,优化氮退火工艺条件以改善MOSFET栅源电压的稳定性,在n型4H-SiC(0001)外延片上制备了横向扩散MOSFET(LDMOSFET)和纵向扩散MOSFET(VDMOSFET)。对栅氧化层采用不同温度、时间和气氛进行氮退火,并对制备的MOSFET进行了HTGB测试,探讨了栅压应力大小、应力时间、温度对栅源电压漂移的影响。结果表明:相比LDMOSFET,VDMOSFET可以更有效地表征栅源电压漂移趋势;氮退火对栅源电压正向漂移影响较小;NO退火后增加高温N_(2)退火、提高NO退火的温度和增加NO退火的时间均会引起VDMOSFET栅源电压负向漂移量增加;当栅压应力为-16 V、应力时间为500 s时,1200℃、70 min NO退火的VDMOSFET的栅源电压漂移比1250℃、40 min NO退火的小0.1~0.3 V。展开更多
氧化矾作为非制冷微测辐射热计的热敏材料,电阻率ρ和电阻温度系数TCR(Temperature Co-efficient of Resistance)是表征其性能的重要参数。通过对用离子束溅射得到的氧化矾薄膜在相同时间不同温度下的N2+H2退火实验,我们发现氧化矾薄膜...氧化矾作为非制冷微测辐射热计的热敏材料,电阻率ρ和电阻温度系数TCR(Temperature Co-efficient of Resistance)是表征其性能的重要参数。通过对用离子束溅射得到的氧化矾薄膜在相同时间不同温度下的N2+H2退火实验,我们发现氧化矾薄膜的电阻率ρ和电阻温度系数TCR之间存在着密切的正相关关系,AES结果表明它们的变化对应着氧化矾热敏材料的O/V比例(或氧空位浓度)的变化。这三个参量随着退火温度的改变而变化,在350～500 ℃的退火温度范围内,我们发现电阻率ρ,电阻温度系数TCR以及O/V比例随着温度的变化均出现一个峰值。通过对氧化矾的电阻温度特性的分析,我们讨论了氧化矾薄膜的导电机制。我们认为,用本方法制备的氧化矾薄膜在室温下导电的载流子主要来自于相对较深能级杂质的电离。展开更多
Chemical doping is an effective method to intrinsically modify the chemical and electronic property of graphene. We propose a novel approach to synthesize the nitrogen-doped graphene via thermal annealing graphene wit...Chemical doping is an effective method to intrinsically modify the chemical and electronic property of graphene. We propose a novel approach to synthesize the nitrogen-doped graphene via thermal annealing graphene with urea, in which the nitrogen source can be controllably released from the urea by varying the annealed temperature and time. The doped N content and the configuration N as well as the thermal stabilities are also evaluated with X-ray photoelectron spectroscopy and Raman spectra. Electrical measurements indi- cate that the conductivity of doped graphene can be well regulated with the N content. The method is expected to produce large scale and controllable N-doped graphene sheets for a variety of potential applications.展开更多
Aiming at developing novel microwave-transparent ceramics with low dielectric loss, high thermal conductivity and high strength, Si3Na-AIN （30%, mass fraction） composite ceramics with La203 as sintering additive wer...Aiming at developing novel microwave-transparent ceramics with low dielectric loss, high thermal conductivity and high strength, Si3Na-AIN （30%, mass fraction） composite ceramics with La203 as sintering additive were prepared by hot-pressing at 1 800 ℃ and subsequently annealed at 1 450 ℃ and 1 850 ℃ for 2 h and 4 h, respectively. The materials were characterized by XRD and SEM. The effect of annealing process on the phase composition, sintering performance, microstructure, bending strength, dielectric loss and thermal conductivity of the materials was investigated. The results showed that both annealing at 1 850 ℃ and 1 450 ℃ promoted the phase transformation of α-Si3N4 to β-Si3N4. After annealing at 1 850 ℃, grain growth to a certain extent occurred in the materials. Especially, the elongated β-Si3N4 grains showed a slight increase in diameter from 0.2 μm to 0.6 μm approximately and a decrease in aspect ratio. As a result, as the annealing time increased to 4 h, the bending strength declined from 456 MPa to 390 MPa, whereas the dielectric loss decreased to 2.15× 10^-3 and the thermal conductivity increased to 16.3 W/（m.K） gradually. When annealed at 1 450 ℃, increasing the annealing time to 4 h significantly promoted the crystallization of glassy phase to La2Si6N803 phase in the materials, which led to the increase in bending strength to 619 MPa and thermal conductivity to 15.9 W/（m·K）, respectively, and simultaneously the decrease in dielectric loss to 1.53× 10^-3.展开更多
Semi-insulating （SI） GaN is grown using N2 as the nucleation layer （NL） carrier gas combined with an optimized annealing time by metalorganic chemical vapour deposition. Influence of using 1-12 and N2 as the NL ca...Semi-insulating （SI） GaN is grown using N2 as the nucleation layer （NL） carrier gas combined with an optimized annealing time by metalorganic chemical vapour deposition. Influence of using 1-12 and N2 as the NL carrier gas is investigated in our experiment. It is found that the sheet resistance of unintentionally doped GaN can be increased from 10^4 Ω/sq to 10^10 Ω/sq by changing the NL carrier gas from 1-12 to N2 while keeping the other growth parameters to be constant, however crystal quality and roughness of the tilm are degraded unambiguously. This situation can be improved by optimizing the NL annealing time. The high resistance of GaN grown on NL using N2 as the carrier gas is due to higher density of threading dislocations caused by the higher density of nucleation islands and small statistic diameter grain compared to the one using 1-12 as carrier gas. Annealing the NL for an optimized annealing time can decrease the density of threading dislocation and improve the tilm roughness and interface of AlGaN/GaN without degrading the sheet resistance of as-grown GaN signiticantly. High-quality SI GaN is grown after optimizing the annealing time, and AlGaN/GaN high electron mobility transistors are also prepared.展开更多
The communication reports an exploratory experimental study on the effects of nitrogen annealing on lithium ion intercalation in nickel-doped lithium trivana- date cathodic electrodes for lithium ion batteries. It sho...The communication reports an exploratory experimental study on the effects of nitrogen annealing on lithium ion intercalation in nickel-doped lithium trivana- date cathodic electrodes for lithium ion batteries. It shows good rate performance with discharge capacities of 348.6, 252.6, 191.9 and 96.7 mAh g-1 at 0.2, 0.5, 1 and 5 C, respectively. Nitrogen annealing resulted in the formation of parasitic secondary-phase LiVzO5 and appreciably increased tetravalent vanadium ions compensated with oxygen vacancies, which would enhance the electronic conductivity and lithium ion diffusivity and promote the interface interaction and deintercalation process, and thus lead to the enhanced lithium ion intercalation properties. The possible impacts of the parasitic secondary-phase LiV205 on the lithium ion intercalation performance have also been discussed.展开更多
We develop a model for the effect of thermal annealing on forming In--N dusters in GalnNP according to thermodynamics. The average energy variation for forming an In--N bond in the model is estimated according to the ...We develop a model for the effect of thermal annealing on forming In--N dusters in GalnNP according to thermodynamics. The average energy variation for forming an In--N bond in the model is estimated according to the theoretical calculation. Using the model, the added number of In--N bonds per mol of InGaNP, the added number of nearest-neighbor In atoms per N atom and the average number of nearest-neighbor In atoms per N atom after annealing are calculated. The different function of In--N clusters in InGaNP and InGaN is also discussed, which is due to the different environments around the In--N clusters.展开更多
文摘为了准确地表征4H-SiC MOSFET经过高温栅偏(HTGB)测试后的栅源电压漂移,优化氮退火工艺条件以改善MOSFET栅源电压的稳定性,在n型4H-SiC(0001)外延片上制备了横向扩散MOSFET(LDMOSFET)和纵向扩散MOSFET(VDMOSFET)。对栅氧化层采用不同温度、时间和气氛进行氮退火,并对制备的MOSFET进行了HTGB测试,探讨了栅压应力大小、应力时间、温度对栅源电压漂移的影响。结果表明:相比LDMOSFET,VDMOSFET可以更有效地表征栅源电压漂移趋势;氮退火对栅源电压正向漂移影响较小;NO退火后增加高温N_(2)退火、提高NO退火的温度和增加NO退火的时间均会引起VDMOSFET栅源电压负向漂移量增加;当栅压应力为-16 V、应力时间为500 s时,1200℃、70 min NO退火的VDMOSFET的栅源电压漂移比1250℃、40 min NO退火的小0.1~0.3 V。
文摘氧化矾作为非制冷微测辐射热计的热敏材料,电阻率ρ和电阻温度系数TCR(Temperature Co-efficient of Resistance)是表征其性能的重要参数。通过对用离子束溅射得到的氧化矾薄膜在相同时间不同温度下的N2+H2退火实验,我们发现氧化矾薄膜的电阻率ρ和电阻温度系数TCR之间存在着密切的正相关关系,AES结果表明它们的变化对应着氧化矾热敏材料的O/V比例(或氧空位浓度)的变化。这三个参量随着退火温度的改变而变化,在350～500 ℃的退火温度范围内,我们发现电阻率ρ,电阻温度系数TCR以及O/V比例随着温度的变化均出现一个峰值。通过对氧化矾的电阻温度特性的分析,我们讨论了氧化矾薄膜的导电机制。我们认为,用本方法制备的氧化矾薄膜在室温下导电的载流子主要来自于相对较深能级杂质的电离。
文摘Chemical doping is an effective method to intrinsically modify the chemical and electronic property of graphene. We propose a novel approach to synthesize the nitrogen-doped graphene via thermal annealing graphene with urea, in which the nitrogen source can be controllably released from the urea by varying the annealed temperature and time. The doped N content and the configuration N as well as the thermal stabilities are also evaluated with X-ray photoelectron spectroscopy and Raman spectra. Electrical measurements indi- cate that the conductivity of doped graphene can be well regulated with the N content. The method is expected to produce large scale and controllable N-doped graphene sheets for a variety of potential applications.
基金Project(50872052) supported by the National Natural Science Foundation of ChinaProject(2009AA05Z313) supported by the National High Technology Research and Development Program of ChinaProject supported by the Commission of Science,Technology and Industry for National Defence,China
文摘Aiming at developing novel microwave-transparent ceramics with low dielectric loss, high thermal conductivity and high strength, Si3Na-AIN （30%, mass fraction） composite ceramics with La203 as sintering additive were prepared by hot-pressing at 1 800 ℃ and subsequently annealed at 1 450 ℃ and 1 850 ℃ for 2 h and 4 h, respectively. The materials were characterized by XRD and SEM. The effect of annealing process on the phase composition, sintering performance, microstructure, bending strength, dielectric loss and thermal conductivity of the materials was investigated. The results showed that both annealing at 1 850 ℃ and 1 450 ℃ promoted the phase transformation of α-Si3N4 to β-Si3N4. After annealing at 1 850 ℃, grain growth to a certain extent occurred in the materials. Especially, the elongated β-Si3N4 grains showed a slight increase in diameter from 0.2 μm to 0.6 μm approximately and a decrease in aspect ratio. As a result, as the annealing time increased to 4 h, the bending strength declined from 456 MPa to 390 MPa, whereas the dielectric loss decreased to 2.15× 10^-3 and the thermal conductivity increased to 16.3 W/（m.K） gradually. When annealed at 1 450 ℃, increasing the annealing time to 4 h significantly promoted the crystallization of glassy phase to La2Si6N803 phase in the materials, which led to the increase in bending strength to 619 MPa and thermal conductivity to 15.9 W/（m·K）, respectively, and simultaneously the decrease in dielectric loss to 1.53× 10^-3.
基金Supported by the Knowledge Innovation Programme of Chinese Academy of Sciences, the National Natural Science Foundation of China under Grant Nos 10474126 and 10574148, and the National Key Basic Research Programme of China under Grant No 2002CB311900.
文摘Semi-insulating （SI） GaN is grown using N2 as the nucleation layer （NL） carrier gas combined with an optimized annealing time by metalorganic chemical vapour deposition. Influence of using 1-12 and N2 as the NL carrier gas is investigated in our experiment. It is found that the sheet resistance of unintentionally doped GaN can be increased from 10^4 Ω/sq to 10^10 Ω/sq by changing the NL carrier gas from 1-12 to N2 while keeping the other growth parameters to be constant, however crystal quality and roughness of the tilm are degraded unambiguously. This situation can be improved by optimizing the NL annealing time. The high resistance of GaN grown on NL using N2 as the carrier gas is due to higher density of threading dislocations caused by the higher density of nucleation islands and small statistic diameter grain compared to the one using 1-12 as carrier gas. Annealing the NL for an optimized annealing time can decrease the density of threading dislocation and improve the tilm roughness and interface of AlGaN/GaN without degrading the sheet resistance of as-grown GaN signiticantly. High-quality SI GaN is grown after optimizing the annealing time, and AlGaN/GaN high electron mobility transistors are also prepared.
基金supported by the‘‘Thousands Talents’’Program for a pioneer researcher and his innovative teamChina+5 种基金supported by the National Natural Science Foundation of China(51374029)the National Science Foundation(NSFDMR-1505902)Program for New Century Excellent Talents in University(NCET-13-0668)Fundamental Research Funds for the Central Universities(FRF-TP-14-008C1)China Postdoctoral Science Foundation(2015M570988)
文摘The communication reports an exploratory experimental study on the effects of nitrogen annealing on lithium ion intercalation in nickel-doped lithium trivana- date cathodic electrodes for lithium ion batteries. It shows good rate performance with discharge capacities of 348.6, 252.6, 191.9 and 96.7 mAh g-1 at 0.2, 0.5, 1 and 5 C, respectively. Nitrogen annealing resulted in the formation of parasitic secondary-phase LiVzO5 and appreciably increased tetravalent vanadium ions compensated with oxygen vacancies, which would enhance the electronic conductivity and lithium ion diffusivity and promote the interface interaction and deintercalation process, and thus lead to the enhanced lithium ion intercalation properties. The possible impacts of the parasitic secondary-phase LiV205 on the lithium ion intercalation performance have also been discussed.
基金supported by the Special Funds for the Major State Basic Research Project (Grant No.2011CB301900)the National Natural Science Foundation of China (Grant Nos.60990311,60820106003,60906025,60936004 and 61177078)+1 种基金the Natural Science Foundation of Jiangsu Province (Grant Nos.BK2008019,BK2010385,BK2009255 and BK2010178)the Research Funds from NJU-Yangzhou Institute of Opto-electronics
文摘We develop a model for the effect of thermal annealing on forming In--N dusters in GalnNP according to thermodynamics. The average energy variation for forming an In--N bond in the model is estimated according to the theoretical calculation. Using the model, the added number of In--N bonds per mol of InGaNP, the added number of nearest-neighbor In atoms per N atom and the average number of nearest-neighbor In atoms per N atom after annealing are calculated. The different function of In--N clusters in InGaNP and InGaN is also discussed, which is due to the different environments around the In--N clusters.
