Doping against the Native Propensity of MoS2: Degenerate Hole Doping by Cation Substitution

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• 作者：Joonki Suh ; Tae-Eon Park ; Der-Yuh Lin ; Deyi Fu ; Joonsuk Park ; Hee Joon Jung ; Yabin Chen ; Changhyun Ko ; Chaun Jang ; Yinghui Sun ; Robert Sinclair ; Joonyeon Chang ; Sefaattin Tongay ; Junqiao Wu
• 刊名：Nano Letters
• 出版年：2014
• 出版时间：December 10, 2014
• 年：2014
• 卷：14
• 期：12
• 页码：6976-6982
• 全文大小：393K
• ISSN：1530-6992

文摘

Layered transition metal dichalcogenides (TMDs) draw much attention as the key semiconducting material for two-dimensional electrical, optoelectronic, and spintronic devices. For most of these applications, both n- and p-type materials are needed to form junctions and support bipolar carrier conduction. However, typically only one type of doping is stable for a particular TMD. For example, molybdenum disulfide (MoS₂) is natively an n-type presumably due to omnipresent electron-donating sulfur vacancies, and stable/controllable p-type doping has not been achieved. The lack of p-type doping hampers the development of charge-splitting p鈥?i>n junctions of MoS₂, as well as limits carrier conduction to spin-degenerate conduction bands instead of the more interesting, spin-polarized valence bands. Traditionally, extrinsic p-type doping in TMDs has been approached with surface adsorption or intercalation of electron-accepting molecules. However, practically stable doping requires substitution of host atoms with dopants where the doping is secured by covalent bonding. In this work, we demonstrate stable p-type conduction in MoS₂ by substitutional niobium (Nb) doping, leading to a degenerate hole density of 鈭? 脳 10¹⁹ cm^鈥?. Structural and X-ray techniques reveal that the Nb atoms are indeed substitutionally incorporated into MoS₂ by replacing the Mo cations in the host lattice. van der Waals p鈥?i>n homojunctions based on vertically stacked MoS₂ layers are fabricated, which enable gate-tunable current rectification. A wide range of microelectronic, optoelectronic, and spintronic devices can be envisioned from the demonstrated substitutional bipolar doping of MoS₂. From the miscibility of dopants with the host, it is also expected that the synthesis technique demonstrated here can be generally extended to other TMDs for doping against their native unipolar propensity.

Keywords:

transition-metal dichalcogenides; molybdenum disulfide; substitutional doping; p-type MoS₂; p鈭?i>n junction