(Invited) The (R)Evolution of the Junctionless Transistor

Abstract

In the junctionless transistor the doping type and concentration in the channel region is essentially equal to that in the source and drain, or at least to that in the source and drain extensions. This paper will first focus on the Revolution of the junctionless transistor, concentrating on the initial reports and studies in 2009. Then the Evolution of the junctionless transistor will be discussed since those early reports in 2009. A variety of studies will be reviewed, as junctionless transistors are being reported in many more materials other than Si, such as in Ge and InGaAs, and very recently in MoS2 and in other transition-metal-dichalcogenide semiconductors.

Junctionless Electric-Double-Layer MoS2 Field-Effect Transistor with a Sub-5 nm Thick Electrostatically Highly Doped Channel

“…Furthermore, junctionless transistors (JLTs) offer benefits for sub-3 nm technology nodes ,− because they are simple structures without p–n junctions and with a highly doped source, channel, and drain; these characteristics significantly reduce the fabrication costs and complexity associated with gate alignment and junction definition. Bulk conduction-based JLTs exhibit resilience to bias stress, lower 1/f noise characteristics, and less mobility degradation when the gate is biased. ,, High-performance sensors and transistors fabricated using nanomaterial JLTs, including two-dimensional transition-metal dichalcogenides, have been reported. , However, in contrast to Si-based JLTs, there have been no systematic analyses of the unique operating properties of nanomaterial-based JLTs.…”

“…5,20,21 High-performance sensors and transistors fabricated using nanomaterial JLTs, including two-dimensional transition-metal dichalcogenides, have been reported. 22,23 However, in contrast to Si-based JLTs, there have been no systematic analyses of the unique operating properties of nanomaterial-based JLTs.…”

Channel thickness-dependent mobility degradation in planar junctionless transistors

“…Junctionless transistor (JLT, also called highly doped accumulation-mode field-effect transistor) is a potential candidate to overcome the short-channel effects for fulfilling the requirements of big data, mobile devices, the Internet of Things and cloud servers with further improved performance of transistors. [1][2][3] Extremely simple structures of JLTs without PN-junctions can eliminate the crucial issues about diffusion of source and drain doping atoms into channel regime. In addition, bulk conduction based operation of JLTs results in reduced degradation of mobility by strong electricfield (E-field) from gate and enables less aggressive scaling of insulator thickness.…”

“…Interestingly, semiconducting multilayer TMDs (transition metal dichalcogenides such as MoS 2 ) based transistors are basically JLTs, since the devices have a uniformly doped source, channel and drain with ohmic-like contacts, and bulk conduction is in play. [3][4][5] The most critical parameters of JLTs are the threshold voltage (V th ) and the flat-band voltage (V fb ), both of which are significantly influenced by the channel doping concentration and the device structures. 6,7) In this paper, we explore the electrical characteristics of planar JLT devices differing in terms of silicon (Si) layer thickness; we used both numerical simulation and analytical modeling.…”

Performance Evaluation of Spacer Dielectric Engineered Vertically Stacked Junctionless Nanosheet FET for Sub-5 nm Technology Node

“…5 So, junctionless (JL) transistors are proposed for continual scaling with easy fabrication processes and reduced the short channel effects (SCE). 6,7 The JL device also provides large on-currents, an approximate ideal subthreshold swing, better output characteristics, and excellent switching properties. 8,9 However, the JL-FETs suffer from impurity scatterings, random doping fluctuations (RDFs), and when the dimensions are scaled to the sub-10 nm region, the JL-FET is also prone to short channel effects (SCE) and further degrades the electrostatic integrity.…”