Understanding Coulomb Scattering Mechanism in Monolayer MoS2 Channel in the Presence of h-BN Buffer Layer

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• 作者：Min-Kyu Joo ; Byoung Hee Moon ; Hyunjin Ji ; Gang Hee Han ; Hyun Kim ; Gwanmu Lee ; Seong Chu LimDongseok Suh ; Young Hee Lee
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：February 8, 2017
• 年：2017
• 卷：9
• 期：5
• 页码：5006-5013
• 全文大小：518K
• ISSN：1944-8252

文摘

As the thickness becomes thinner, the importance of Coulomb scattering in two-dimensional layered materials increases because of the close proximity between channel and interfacial layer and the reduced screening effects. The Coulomb scattering in the channel is usually obscured mainly by the Schottky barrier at the contact in the noise measurements. Here, we report low-temperature (T) noise measurements to understand the Coulomb scattering mechanism in the MoSb>2b> channel in the presence of h-BN buffer layer on the silicon dioxide (SiOb>2b>) insulating layer. One essential measure in the noise analysis is the Coulomb scattering parameter (αb>SCb>) which is different for channel materials and electron excess doping concentrations. This was extracted exclusively from a 4-probe method by eliminating the Schottky contact effect. We found that the presence of h-BN on SiOb>2b> provides the suppression of αb>SCb> twice, the reduction of interfacial traps density by 100 times, and the lowered Schottky barrier noise by 50 times compared to those on SiOb>2b> at T = 25 K. These improvements enable us to successfully identify the main noise source in the channel, which is the trapping–detrapping process at gate dielectrics rather than the charged impurities localized at the channel, as confirmed by fitting the noise features to the carrier number and correlated mobility fluctuation model. Further, the reduction in contact noise at low temperature in our system is attributed to inhomogeneous distributed Schottky barrier height distribution in the metal–MoSb>2b> contact region.