The instability of p-channel low-temperature polycrystalline silicon thin film transistors(poly-Si TFTs)is investigated under negative gate bias stress(NBS)in this work.Firstly,a series of negative bias stress experim...The instability of p-channel low-temperature polycrystalline silicon thin film transistors(poly-Si TFTs)is investigated under negative gate bias stress(NBS)in this work.Firstly,a series of negative bias stress experiments is performed,the significant degradation behaviors in current-voltage characteristics are observed.As the stress voltage decreases from-25 V to-37 V,the threshold voltage and the sub-threshold swing each show a continuous shift,which is induced by gate oxide trapped charges or interface state.Furthermore,low frequency noise(LFN)values in poly-Si TFTs are measured before and after negative bias stress.The flat-band voltage spectral density is extracted,and the trap concentration located near the Si/SiO2 interface is also calculated.Finally,the degradation mechanism is discussed based on the current-voltage and LFN results in poly-Si TFTs under NBS,finding out that Si-OH bonds may be broken and form Si*and negative charge OH-under negative bias stress,which is demonstrated by the proposed negative charge generation model.展开更多
A new technique for designing a varactor-tunable frequency selective surface （FSS） with an embedded bias network is proposed and experimentally verified. The proposed FSS is based on a square-ring slot FSS. The freq...A new technique for designing a varactor-tunable frequency selective surface （FSS） with an embedded bias network is proposed and experimentally verified. The proposed FSS is based on a square-ring slot FSS. The frequency tuning is achieved by inserting varactor diodes between the square mesh and each unattached square patch. The square mesh is divided into two parts for biasing the varactor diodes. Full-wave numerical simulations show that a wide tuning range can be achieved by changing the capacitances of these loaded varactors. Two homo-type samples using fixed lumped capacitors are fabricated and measured using a standard waveguide measurement setup. Excellent agreement between the measured and simulated results is demonstrated.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61574048)the Pearl River Science and Technology Nova Program of Guangzhou City,China(Grant No.201710010172)+2 种基金the International Science and Technology Cooperation Program of Guangzhou City(Grant No.201807010006)the International Cooperation Program of Guangdong Province,China(Grant No.2018A050506044)the Opening Fund of Key Laboratory of Silicon Device Technology,China(Grant No.KLSDTJJ2018-6)
文摘The instability of p-channel low-temperature polycrystalline silicon thin film transistors(poly-Si TFTs)is investigated under negative gate bias stress(NBS)in this work.Firstly,a series of negative bias stress experiments is performed,the significant degradation behaviors in current-voltage characteristics are observed.As the stress voltage decreases from-25 V to-37 V,the threshold voltage and the sub-threshold swing each show a continuous shift,which is induced by gate oxide trapped charges or interface state.Furthermore,low frequency noise(LFN)values in poly-Si TFTs are measured before and after negative bias stress.The flat-band voltage spectral density is extracted,and the trap concentration located near the Si/SiO2 interface is also calculated.Finally,the degradation mechanism is discussed based on the current-voltage and LFN results in poly-Si TFTs under NBS,finding out that Si-OH bonds may be broken and form Si*and negative charge OH-under negative bias stress,which is demonstrated by the proposed negative charge generation model.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60901029, 61172148, and 60925005)the Natural Science Foundation of Shaanxi Province, China (Grant No. 2011JQ8040)
文摘A new technique for designing a varactor-tunable frequency selective surface （FSS） with an embedded bias network is proposed and experimentally verified. The proposed FSS is based on a square-ring slot FSS. The frequency tuning is achieved by inserting varactor diodes between the square mesh and each unattached square patch. The square mesh is divided into two parts for biasing the varactor diodes. Full-wave numerical simulations show that a wide tuning range can be achieved by changing the capacitances of these loaded varactors. Two homo-type samples using fixed lumped capacitors are fabricated and measured using a standard waveguide measurement setup. Excellent agreement between the measured and simulated results is demonstrated.
