113學年材料所-第八週 專題研討課程 演講公告 (114年4月10日)

演講題目:
Surface-dominant Electronic Transport in MoS₂ and MoSe₂ Layered Semiconductors

演講者: 陳瑞山教授(Prof. Ruei-San Chen) 
現職: 國立台灣科技大學      應用科技研究所    教授
時間: 114年04月10日(四) 下午15:20~17:10
地點: 成功大學成功校區三系館 鋼構區(3F)共同教室A1302演講廳

內容摘要:
Van der Waals crystals are expected to have an inert surface because of the absence of dangling bonds. However, our study revealed that the surface of high-quality molybdenum disulfide (MoS₂) and molybdenum diselenide (MoSe₂) is a major n-doping source. The surface electron concentration of MoS₂ and MoSe₂ are nearly four orders of magnitude higher than that of its inner bulk. The substantial thickness-dependent conductivity in MoS₂ and MoSe₂ nanoflakes were observed. Scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES) measurements confirmed the presence of surface electron accumulation (SEA) in these layer materials. Notably, the pronounced n-doping characteristic was not observed in the cleaved fresh surface of MoS₂. The in-situ ARPES measurement indicates that the cleaved MoS₂ fresh surface exhibits a near intrinsic state without SEA.
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