In this work,grain boundary(GB)potential barrier(ΔφGB),dopant density(Pnet),and filled trap state density(PGB,trap)were manipulated at the nanoscale by exposing the fabricated perovskite films to various relative hu...In this work,grain boundary(GB)potential barrier(ΔφGB),dopant density(Pnet),and filled trap state density(PGB,trap)were manipulated at the nanoscale by exposing the fabricated perovskite films to various relative humidity(RH)environments.Spatial mapping of surface potential in the perovskite film revealed higher positive potential at GBs than inside the grains.The averageΔφGB,Pnet,and PGB,trap in the perovskite films decreased from 0%RH to 25%RH exposure,but increased when the RH increased to 35%RH and 45%RH.This clearly indicated that perovskite solar cells fabricated at 25%RH led to the lowest average GB potential,smallest dopant density,and least filled trap states density.This is consistent with the highest photovoltaic efficiency of 18.16%at 25%RH among the different relative humidities from 0%to 45%RH.展开更多
3C-SiC is a promising structural material for piezoresistive sensors used in high-temperature applications. For sensor development, the preparation of sensor materials and study of its electrical properties, such as r...3C-SiC is a promising structural material for piezoresistive sensors used in high-temperature applications. For sensor development, the preparation of sensor materials and study of its electrical properties, such as resistivity, barrier height of grain boundaries, and temperature coefficient of resistivity, are important in addition to structural properties and these have to be optimized. In the present work, 3C-SiC thin film with in situ doping of nitrogen is prepared through low- pressure chemical vapor deposition by using methyl trichloro silane, ammonia, and hydrogen as precursors. Electrical properties of deposited 3C-SiC thin films with varying nitrogen doping concentration through four probe technique are studied. Atomic force microscopy investigations are carried out to study the grain size on and average root-mean-squared roughness 3C-SiC thin films. A decrease in the degree of crystallinity is observed in nitrogen-doped 3C-SiC thin films. The sheet resistivity of nitrogen-doped 3C-SiC thin film is found to decrease with increase in temperature in the range from 303 to 823 K. The sheet resistivity, average temperature coefficient of resistance, and barrier height of the grain boundaries of film doped with 17 at.% of nitrogen are 0.14 cm, -1.0 x 10-n/K, and 0.01 eV, respectively. Comparing all the nitrogen-doped 3C-SiC thin films, the film doped with 17 at.% of nitrogen exhibits an improved structural and electrical properties and it can be used as sensing material for high-temperature applications.展开更多
基金This work has been supported in part by NSF MRI(1428992)NASA EPSCoR(NNX15AM83A)+3 种基金U.S.-Egypt Science and Technology(S&T)Joint Fund,SDBoR R&D Program,and EDA University Center Program(ED18DEN3030025)This work is derived from the Subject Data supported in whole or part by NAS and USAID,and any opinions,findings,conclusions,or recommendations expressed in the paper are those of the authors alone,and do not necessarily reflect the views of USAID or NAS.We would like to thank Dr Brian Moore for assisting us with high performance computing facility at South Dakota State University.W.Y.acknowledges the support from International Cooperation Project of Anhui Province(1503062018)Visiting Research Scholar Project for Young/Middle Excellent Talents of Anhui Province(gxfxZD2016110)Preeminent Youth Foundation of Anhui Polytechnic University(2016JQ002).
文摘In this work,grain boundary(GB)potential barrier(ΔφGB),dopant density(Pnet),and filled trap state density(PGB,trap)were manipulated at the nanoscale by exposing the fabricated perovskite films to various relative humidity(RH)environments.Spatial mapping of surface potential in the perovskite film revealed higher positive potential at GBs than inside the grains.The averageΔφGB,Pnet,and PGB,trap in the perovskite films decreased from 0%RH to 25%RH exposure,but increased when the RH increased to 35%RH and 45%RH.This clearly indicated that perovskite solar cells fabricated at 25%RH led to the lowest average GB potential,smallest dopant density,and least filled trap states density.This is consistent with the highest photovoltaic efficiency of 18.16%at 25%RH among the different relative humidities from 0%to 45%RH.
文摘3C-SiC is a promising structural material for piezoresistive sensors used in high-temperature applications. For sensor development, the preparation of sensor materials and study of its electrical properties, such as resistivity, barrier height of grain boundaries, and temperature coefficient of resistivity, are important in addition to structural properties and these have to be optimized. In the present work, 3C-SiC thin film with in situ doping of nitrogen is prepared through low- pressure chemical vapor deposition by using methyl trichloro silane, ammonia, and hydrogen as precursors. Electrical properties of deposited 3C-SiC thin films with varying nitrogen doping concentration through four probe technique are studied. Atomic force microscopy investigations are carried out to study the grain size on and average root-mean-squared roughness 3C-SiC thin films. A decrease in the degree of crystallinity is observed in nitrogen-doped 3C-SiC thin films. The sheet resistivity of nitrogen-doped 3C-SiC thin film is found to decrease with increase in temperature in the range from 303 to 823 K. The sheet resistivity, average temperature coefficient of resistance, and barrier height of the grain boundaries of film doped with 17 at.% of nitrogen are 0.14 cm, -1.0 x 10-n/K, and 0.01 eV, respectively. Comparing all the nitrogen-doped 3C-SiC thin films, the film doped with 17 at.% of nitrogen exhibits an improved structural and electrical properties and it can be used as sensing material for high-temperature applications.
