Esaki Diodes in van der Waals Heterojunctions with Broken-Gap Energy Band Alignment

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• 作者：Rusen Yan ; Sara Fathipour ; Yimo Han ; Bo Song ; Shudong Xiao ; Mingda Li ; Nan Ma ; Vladimir Protasenko ; David A. Muller ; Debdeep Jena ; Huili Grace Xing
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：September 9, 2015
• 年：2015
• 卷：15
• 期：9
• 页码：5791-5798
• 全文大小：408K
• ISSN：1530-6992

文摘

van der Waals (vdW) heterojunctions composed of two-dimensional (2D) layered materials are emerging as a solid-state materials family that exhibits novel physics phenomena that can power a range of electronic and photonic applications. Here, we present the first demonstration of an important building block in vdW solids: room temperature Esaki tunnel diodes. The Esaki diodes were realized in vdW heterostructures made of black phosphorus (BP) and tin diselenide (SnSe₂), two layered semiconductors that possess a broken-gap energy band offset. The presence of a thin insulating barrier between BP and SnSe₂ enabled the observation of a prominent negative differential resistance (NDR) region in the forward-bias current鈥搗oltage characteristics, with a peak to valley ratio of 1.8 at 300 K and 2.8 at 80 K. A weak temperature dependence of the NDR indicates electron tunneling being the dominant transport mechanism, and a theoretical model shows excellent agreement with the experimental results. Furthermore, the broken-gap band alignment is confirmed by the junction photoresponse, and the phosphorus double planes in a single layer of BP are resolved in transmission electron microscopy (TEM) for the first time. Our results represent a significant advance in the fundamental understanding of vdW heterojunctions and broaden the potential applications of 2D layered materials.