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MoTe2 Lateral Homojunction Field-Effect Transistors Fabricated using Flux-Controlled Phase Engineering
ACS Nano ( IF 15.8 ) Pub Date : 2019-06-27 00:00:00 , DOI: 10.1021/acsnano.9b02785
Rui Ma 1 , Huairuo Zhang 2, 3 , Youngdong Yoo 4 , Zachary Patrick Degregorio 5 , Lun Jin 5 , Prafful Golani 1 , Javad Ghasemi Azadani 1 , Tony Low 1 , James E. Johns 5 , Leonid A. Bendersky 3 , Albert V. Davydov 3 , Steven J. Koester 1
Affiliation  

The coexistence of metallic and semiconducting polymorphs in transition-metal dichalcogenides (TMDCs) can be utilized to solve the large contact resistance issue in TMDC-based field effect transistors (FETs). A semiconducting hexagonal (2H) molybdenum ditelluride (MoTe2) phase, metallic monoclinic (1T′) MoTe2 phase, and their lateral homojunctions can be selectively synthesized in situ by chemical vapor deposition due to the small free energy difference between the two phases. Here, we have investigated, in detail, the structural and electrical properties of in situ-grown lateral 2H/1T′ MoTe2 homojunctions grown using flux-controlled phase engineering. Using atomic-resolution plan-view and cross-sectional transmission electron microscopy analyses, we show that the round regions of near-single-crystalline 2H-MoTe2 grow out of a polycrystalline 1T′-MoTe2 matrix. We further demonstrate the operation of MoTe2 FETs made on these in situ-grown lateral homojunctions with 1T′ contacts. The use of a 1T′ phase as electrodes in MoTe2 FETs effectively improves the device performance by substantially decreasing the contact resistance. The contact resistance of 1T′ electrodes extracted from transfer length method measurements is 470 ± 30 Ω·μm. Temperature- and gate-voltage-dependent transport characteristics reveal a flat-band barrier height of ∼30 ± 10 meV at the lateral 2H/1T′ interface that is several times smaller and shows a stronger gate modulation, compared to the metal/2H Schottky barrier height. The information learned from this analysis will be critical to understanding the properties of MoTe2 homojunction FETs for use in memory and logic circuity applications.

中文翻译:

使用磁通控制相工程制造的MoTe 2横向同质结场效应晶体管

金属和半导体多晶型物在过渡金属二卤化物(TMDC)中的共存可用于解决基于TMDC的场效应晶体管(FET)中的大接触电阻问题。由于两相之间的自由能差小,可以通过化学气相沉积法原位合成半六角形(2H)二碲化钼(MoTe 2)相,金属单斜相(1T')MoTe 2相及其横向同质结。在这里,我们详细研究了原位生长的横向2H / 1T'MoTe 2的结构和电学性能使用通量控制相工程技术生长的同质结。使用原子分辨率的平面图和横截面透射电子显微镜分析,我们表明,接近单晶的2H-MoTe 2的圆形区域长出了多晶的1T'-MoTe 2基质。我们进一步演示了具有1T'触点的这些原位生长的横向同质结上制造MoTe 2 FET的操作。在MoTe 2中使用1T'相作为电极FET通过大大降低接触电阻有效地改善了器件性能。从转移长度法测量中提取的1T'电极的接触电阻为470±30Ω·μm。与温度和栅极电压有关的传输特性表明,与金属/ 2H肖特基相比,在侧面2H / 1T'界面处的平坦带势垒高度约为30±10 meV,该高度减小了几倍,并显示出更强的栅极调制能力障碍物高度。从该分析中学到的信息对于理解用于存储器和逻辑电路应用的MoTe 2同质结FET的特性至关重要。
更新日期:2019-06-27
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