Charge transport and optoelectronic properties of black phosphorus/rhenium diselenide heterojunction

• Main Authors: Wan, Chi-Kai, 萬騏愷
• Other Authors: Jian, Wen-Bin
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/a9n5vk

碩士 === 國立交通大學 === 電子物理系所 === 106 === We used mechanical exfoliation to make ultrathin flakes of black phosphorus (BP) and rhenium diselenide (ReSe2). Then we stacked them together on a silicon substrate by our homemade machine of 2D materials alignment and stacking system. Electron beam lithography and thermal evaporation were used to fabricate Au electrodes on the stacked BP/ReSe2 flakes. The contacts of the devices were improved by rapid thermal annealing. The electrical measurements revealed that BP is p-type and ReSe2 is n-type semiconductors. In particular, we studied current-voltage (IDS-VDS) curves of the BP/ReSe2 heterojunction that displayed a PN diode behavior. A big rectification ratio of ~104 is observed in our BP/ReSe2 heterojunction devices. It is observed that field-dependent charge transport of the BP/ReSe2 heterojunction shows either direct or Fowler-Nordheim (F-N) tunneling behaviors, depending on the applied bias voltages. According to the F-N tunneling model, we learned the dependency of carrier concentration on the junction barrier height. On the other hand, we studied optoelectronic properties of the BP/ReSe2 heterojunction under light exposure of the He-Ne laser. The BP/ReSe2 heterojunction showed gate-tunable power conversion efficiencies with the highest value of ~0.73 %. At different gating voltages, we observed varied maximum power conversion efficiencies depending strongly on the build-in voltage. The BP/ReSe2 heterojunction also exhibited gate-tunable external quantum efficiency with the highest value up to 348.8 %. We demonstrated that the BP/ReSe2 heterojunction presents high potential for the application in either solar cells or field-effect photodetectors.