Abstract
Two-dimensional (2D) InSe-based field effect transistor (FET) has shown remarkable carrier mobility and high on-off ratio in experimental reports. Theoretical investigations also predicated the high performance can be well preserved at sub-10 nm nodes in the ballistic limit. However, both experimental experience and theoretical calculations pointed out achieving high-quality ohmic has become the main limiting factor for high-performance 2D FET. In this work, we proposed a new sandwiched ohmic contact with indium for InSe FET and comprehensively evaluated its performance from views of material and device based on ab initio methods. The material properties denote that all of fundamental issues of ohmic contact including tunneling barrier, the Schottky barrier, and effective doping are well concerned by introducing the sandwiched structure, and excellent contact resistance was achieved. At device performance level, devices with gate length of 7, 5, and 3 nm were investigated. All metrics of sandwiched contacted devices far exceed requirement of the International Technology Roadmap for Semiconductors (ITRS) and exhibit obvious promotion as compared to conventional structures. Maximum boost of current with 69.4%, 50%, and 49% are achieved for devices with 7, 5, and 3 nm gate length, respectively. Meanwhile, maximum reduction of the intrinsic delay with 20.4%, 16.7%, and 18.9% are attained. Moreover, a benchmark of energy-delay product (EDP) against other 2D FETs is presented. All InSe FETs with sandwiched ohmic contact surpass MoS2 FETs as well as requirement from ITRS 2024. The best result approaches the upper limit of ideal BP FET, denoting superior preponderance of sandwiched structures for InSe FETs in the next generation of complementary metal-oxide semiconductor (CMOS) technology.
Highlights
Two-dimensional (2D) semiconductors have attracted much interest in electronic devices due to their appealing applications for the generation of complementary metal-oxide semiconductor (CMOS) technology [1, 2]
In general, there are three key factors correlated to the ohmic contact quality in 2D materials [18], i.e., the tunneling barrier and distance which is derived from van der Waals (vdW) gap, orbital overlap between electrode and semiconductor, and the Schottky barrier (SB) height
In this work, a new sandwiched ohmic contact with indium was proposed for indium selenide (InSe) field effect transistor (FET)
Summary
Two-dimensional (2D) semiconductors have attracted much interest in electronic devices due to their appealing applications for the generation of complementary metal-oxide semiconductor (CMOS) technology [1, 2]. Their ultra-thin thickness and good dielectric property can provide excellent electrostatic gate control to suppress the well-known short channel effects [3]. As reliable doping method and way to high-quality ohmic contact are still lacking, FETs based on 2D materials including InSe are usually Schottky barrier (SB) FET [13–16]. Achieving low contact resistance with sufficiently doped active regions has become the main limiting factor for 2D materials-based FET (2D FET) to achieve high performance [17–19]
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