Field plate(FP)-terminated 4H-SiC trench gate MOSFETs are demonstrated in this work.N+/P?/N?/N+multiple epitaxial layers were grown on 3-inch N+type 4H-SiC substrate by chemical vapor deposition(CVD),and then the 4H-S...Field plate(FP)-terminated 4H-SiC trench gate MOSFETs are demonstrated in this work.N+/P?/N?/N+multiple epitaxial layers were grown on 3-inch N+type 4H-SiC substrate by chemical vapor deposition(CVD),and then the 4H-SiC trench gate MOSFETs were fabricated based on the standard trench transistor fabrication.Current-voltage measurements in forward and reverse bias have been performed on different devices with and without FP protections.It is found that more than 60%of the devices protected with FP termination are able to block 850 V.The measurements also show that the devices have the small leakage currents 0.15 nA at 600 V and 2.5 nA at 800 V,respectively.The experimental results also were compared with the simulated results,which show good agreement with each other in the trend.The limited performance of the devices is mainly because of the damage induced on the trench sidewalls from the etching process and the quality of the SiO2 films.Therefore,the 4H-SiC trench gate MOSFETs are expected to be optimized by reducing the etching damage and growing high-quality SiO2 dielectric films.展开更多
GaN PIN betavoltaic nuclear batteries are demonstrated in this work. GaN epitaxial layers were grown on 2-inch sapphire sub-strates by MOCVD, and then the GaN PIN nuclear batteries were fabricated. Current-voltage （...GaN PIN betavoltaic nuclear batteries are demonstrated in this work. GaN epitaxial layers were grown on 2-inch sapphire sub-strates by MOCVD, and then the GaN PIN nuclear batteries were fabricated. Current-voltage （l-V） characteristic shows that the small leakage currents are 0.12 nA at 0 V and 1.76 nA at -10 V, respectively. With 147Pm the irradiation source, the maximum open circuit voltage and maximum short circuit current are 1.07 V and 0.554 nA, respectively. The fill factor （FF） of 24.7% for the battery was been obtained. The limited performance of the devices is mainly due to the low energy deposition in the microbatteries. Therefore, the GaN nuclear microbatteries are expected to be optimized by growing high quality GaN films, thin dead layer and so on.展开更多
In a seminal work, Gozar et al. reported on the high-temperature interface superconductivity in bilayers of insulating La2Cu O4 and metallic La2-xSrxCuO4(x=0.45). An interesting question to address is how general and ...In a seminal work, Gozar et al. reported on the high-temperature interface superconductivity in bilayers of insulating La2Cu O4 and metallic La2-xSrxCuO4(x=0.45). An interesting question to address is how general and robust this interface superconductivity is. In the past, the cuprate bilayers were grown in a unique atomic-layer molecular beam epitaxy system, with a Sr doping range of x≤0.47, and the atomically flat interface was thought to be indispensable. Here, we have fabricated bilayers of La2CuO4 and La2-xSrxCuO4 by pulsed laser deposition. We have tried to extend the nominal doping range of Sr from the previous maximum of 0.47 to the present1.70(the nominal Sr content in the targets). X-ray diffraction result indicates that our La2-xSrxCuO4 films with x≤0.60 have very high crystalline quality;but the film crystalline structure degrades gradually with further increasing x, and finally the structure is fully lost when x reaches 1.40 and higher. Although the film quality scatters dramatically, our experiments show that there exists superconductivity for bilayers in nearly the entire over-doped Sr range, except for a non-superconducting region at x^0.80. These observations demonstrate that the interface superconductivity in copper oxides is very general and robust.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.61176070,61274079)the Natural Science Foundation of Shaanxi Province(Grant No.2013JQ8012)+1 种基金the Doctoral Fund of Ministry of Education of China(Grant Nos.20110203110010,201302031-0017)the Key Specific Projects of Ministry of Education of China(Grant No.625010101)
文摘Field plate(FP)-terminated 4H-SiC trench gate MOSFETs are demonstrated in this work.N+/P?/N?/N+multiple epitaxial layers were grown on 3-inch N+type 4H-SiC substrate by chemical vapor deposition(CVD),and then the 4H-SiC trench gate MOSFETs were fabricated based on the standard trench transistor fabrication.Current-voltage measurements in forward and reverse bias have been performed on different devices with and without FP protections.It is found that more than 60%of the devices protected with FP termination are able to block 850 V.The measurements also show that the devices have the small leakage currents 0.15 nA at 600 V and 2.5 nA at 800 V,respectively.The experimental results also were compared with the simulated results,which show good agreement with each other in the trend.The limited performance of the devices is mainly because of the damage induced on the trench sidewalls from the etching process and the quality of the SiO2 films.Therefore,the 4H-SiC trench gate MOSFETs are expected to be optimized by reducing the etching damage and growing high-quality SiO2 dielectric films.
基金supported by the National Natural Science Foundation of China(Grant No.10875084)the Natural Science Foundation of Jiangsu Province(Grant No.BK2008174)+2 种基金the Applied Science Foundation of Suzhou(Grant No.SYJG0915)the National Basic Research Program of China(Grant No.G2009CB929300)supported by Department of Nuclear Science and Engineering,Nanjing University of Aeronautics and Astronautics
文摘GaN PIN betavoltaic nuclear batteries are demonstrated in this work. GaN epitaxial layers were grown on 2-inch sapphire sub-strates by MOCVD, and then the GaN PIN nuclear batteries were fabricated. Current-voltage （l-V） characteristic shows that the small leakage currents are 0.12 nA at 0 V and 1.76 nA at -10 V, respectively. With 147Pm the irradiation source, the maximum open circuit voltage and maximum short circuit current are 1.07 V and 0.554 nA, respectively. The fill factor （FF） of 24.7% for the battery was been obtained. The limited performance of the devices is mainly due to the low energy deposition in the microbatteries. Therefore, the GaN nuclear microbatteries are expected to be optimized by growing high quality GaN films, thin dead layer and so on.
基金supported by the National Key Research and Development Program of Ministry of Science and Technology of China (2017YFA0303002, 2016YFA0300204, and 2016YFA0300701)the Fundamental Research Funds for the Central Universities
文摘In a seminal work, Gozar et al. reported on the high-temperature interface superconductivity in bilayers of insulating La2Cu O4 and metallic La2-xSrxCuO4(x=0.45). An interesting question to address is how general and robust this interface superconductivity is. In the past, the cuprate bilayers were grown in a unique atomic-layer molecular beam epitaxy system, with a Sr doping range of x≤0.47, and the atomically flat interface was thought to be indispensable. Here, we have fabricated bilayers of La2CuO4 and La2-xSrxCuO4 by pulsed laser deposition. We have tried to extend the nominal doping range of Sr from the previous maximum of 0.47 to the present1.70(the nominal Sr content in the targets). X-ray diffraction result indicates that our La2-xSrxCuO4 films with x≤0.60 have very high crystalline quality;but the film crystalline structure degrades gradually with further increasing x, and finally the structure is fully lost when x reaches 1.40 and higher. Although the film quality scatters dramatically, our experiments show that there exists superconductivity for bilayers in nearly the entire over-doped Sr range, except for a non-superconducting region at x^0.80. These observations demonstrate that the interface superconductivity in copper oxides is very general and robust.
