We study the nucleation mechanism and morphology evolution of MoS2 flakes grown by chemical vapor deposition （CVD） on SiO2/Si substrates with using S and MoO3 powders. The MoS2 flake is of monolayer with triangular ...We study the nucleation mechanism and morphology evolution of MoS2 flakes grown by chemical vapor deposition （CVD） on SiO2/Si substrates with using S and MoO3 powders. The MoS2 flake is of monolayer with triangular nucleation, which might arise from the initial MoO3-x that is deposited on the substrate, and then bonded with S to form MoS2 flake. The ratio of Mo and S is higher than 1：2 at the beginning with Mo terminated triangular nucleation formed. After that, the morphology of MoS2 flake evolves from triangle to similar hexagon, then to truncated triangle which is determined by the faster growth speed of Mo termination than that of S termination under the S rich environment. The nucleation density does not increase linearly with the increase of reactant concentration, which could be explained by the two-dimensional nucleation theory.展开更多
Amorphous–microcrystalline MoS_(2)thin films are fabricated using the sol-gel method to produce MoS_(2)/Si-based solar cells. The generation mechanisms of the S-shaped current density–voltage(J–V) curves of the sol...Amorphous–microcrystalline MoS_(2)thin films are fabricated using the sol-gel method to produce MoS_(2)/Si-based solar cells. The generation mechanisms of the S-shaped current density–voltage(J–V) curves of the solar cells are analyzed. To improve the performance of the solar cells and address the problem of the S-shaped J–V curve, a MoS_(2)film and a p^(+) layer are introduced into the front and back interfaces of the solar cell, respectively, which leads to the formation of a p–n junction between the p-Si and the MoS_(2)film as well as ohmic contacts between the MoS_(2)film and the ITO, improving the S-shaped J–V curve. As a result of the high doping characteristics and the high work function of the p^(+) layer, a high–low junction is formed between the p;and p layers along with ohmic contacts between the p;layer and the Ag electrode. Consequently,the S-shaped J–V curve is eliminated, and a significantly higher current density is achieved at a high voltage. The device exhibits ideal p–n junction rectification characteristics and achieves a high power-conversion efficiency(CE) of 7.55%. The findings of this study may improve the application of MoS_(2)thin films in silicon-based solar cells, which are expected to be widely used in various silicon-based electronic and optical devices.展开更多
基金Project supported by the National Natural Science Foundation of China for Youths(Grant No.61504036)the Natural Science Foundation of Hebei Province for Youths,China(Grant No.A2016201087)+1 种基金the Doctoral Fund of the Ministry of Education of China(Grant No.20131301120003)the Science and Technology Project of Hebei Province,China(Grant No.13214315)
文摘We study the nucleation mechanism and morphology evolution of MoS2 flakes grown by chemical vapor deposition （CVD） on SiO2/Si substrates with using S and MoO3 powders. The MoS2 flake is of monolayer with triangular nucleation, which might arise from the initial MoO3-x that is deposited on the substrate, and then bonded with S to form MoS2 flake. The ratio of Mo and S is higher than 1：2 at the beginning with Mo terminated triangular nucleation formed. After that, the morphology of MoS2 flake evolves from triangle to similar hexagon, then to truncated triangle which is determined by the faster growth speed of Mo termination than that of S termination under the S rich environment. The nucleation density does not increase linearly with the increase of reactant concentration, which could be explained by the two-dimensional nucleation theory.
基金Project supported by the Science and Technology Research Project of Hebei Province Colleges and Universities (Grant No. QN2020113)Tangshan Applied Basic Research Project (Grant No. 19130227g)。
文摘Amorphous–microcrystalline MoS_(2)thin films are fabricated using the sol-gel method to produce MoS_(2)/Si-based solar cells. The generation mechanisms of the S-shaped current density–voltage(J–V) curves of the solar cells are analyzed. To improve the performance of the solar cells and address the problem of the S-shaped J–V curve, a MoS_(2)film and a p^(+) layer are introduced into the front and back interfaces of the solar cell, respectively, which leads to the formation of a p–n junction between the p-Si and the MoS_(2)film as well as ohmic contacts between the MoS_(2)film and the ITO, improving the S-shaped J–V curve. As a result of the high doping characteristics and the high work function of the p^(+) layer, a high–low junction is formed between the p;and p layers along with ohmic contacts between the p;layer and the Ag electrode. Consequently,the S-shaped J–V curve is eliminated, and a significantly higher current density is achieved at a high voltage. The device exhibits ideal p–n junction rectification characteristics and achieves a high power-conversion efficiency(CE) of 7.55%. The findings of this study may improve the application of MoS_(2)thin films in silicon-based solar cells, which are expected to be widely used in various silicon-based electronic and optical devices.
