MOSFET's negative transconductance at room temperature

Vertical Charge Transport and Negative Transconductance in Multilayer Molybdenum Disulfides

“…Herein we report a systematic investigation of charge transport behavior in multilayer 2DSC transistors with optimized van der Waals contact and for the first time demonstrate a vertical built-in potential inside 2DSC (such as MoS 2 , WSe 2 ) can dictate the vertical charge transport to result in a negative transconductance (NTC) behavior, representing a new mechanism for NTC operation besides previous theories based on quantum mechanical tunneling − and mobility degradation. − A systematical investigation of the measurement temperature, body thickness, and screening length reveals that the unique NTC behavior originates from a vertical potential barrier formed in the 2DSC from near-substrate region to bulk region due to different doping mechanisms and inhomogeneous carrier distributions, which is distinct from conventional semiconductor with homogeneous doping defined by bulk dopants. With this NTC behavior, we further show that a single transistor can be used to create frequency doublers and phase shift keying circuits.…”

“…The contact resistance (R contact ) shows a similar trend to R total and contributes >90% of R total at large gate voltage (blue curve). Together, we can attribute the NTC and antibipolar behavior to the contact effect within multilayer devices, excluding the possible contribution from the channel area (e.g., channel mobility degradation or thermal effects 32 ). We would note that within multilayer devices the contact resistance not only includes the resistance at metal-stack−MoS 2 interface but also the resistance of interlayer vertical transport from top to bottom MoS2 layers, which will be further discussed in detail below.…”

Negative transconductance effect in p-GaN gate AlGaN/GaN HEMTs by traps in unintentionally doped GaN buffer layer*

“…[14] Negative transconductance means the decrease in drain current at a large gate voltage, and can be affected by these traps. Earlier researches have revealed the mechanisms of negative transconductance, such as the increase of the intrinsic base resistance in AlGaAs/GaAs HBTs, [15] the electric field distribution in the channel in HFETs, [16] surface-roughness in MOSFETs, [17] and electrode space in MIS tunnel diode. [18] And more recently, negative transconductance were found in MoS 2 /Wse 2 heterojunction transistor.…”

Remote Gate-Controlled Negative Transconductance in Gated MIS Tunnel Diode

“…A variety of transistors have been discovered with NT behavior, like resonant-tunneling transistors [4], [5], modulation-doped FETs [6], [7], MOSFETs [8], [9], and tunneling FETs [3], [10]. However, most of their peak-to-valley current ratios (PVCR) are less than 10, which are not high enough for the applications.…”