High Mobilities in Layered InSe Transistors with Indium‐Encapsulation‐Induced Surface Charge Doping

Abstract

graphene in 2004, diverse layered transition metal dichalcogenides with tunable band gaps have been shown to exhibit extraordinary electrical and optical properties in logic circuits, photodetectors, light-emitting diodes, gas sensors, and energy storage devices. [7][8][9][10][11][12][13][14] However, owing to their low mobility ceiling of a few hundred cm 2 V −1 s −1 , 2D-based fieldeffect transistors (FETs) still encounter a bottleneck for their application in highfrequency electronic devices. In this regard, indium selenide (InSe), with ultrahigh mobility near 1000 cm 2 V −1 s −1 at room temperature, has successfully attracted attention as one of the burgeoning III-VI group layered metal chalcogenides. The van der Waals layered Se-In-In-Se stacked structure, with a smooth surface and narrow band gap (1.26 eV), exhibits a perfect photoresponse to the visible spectrum. [15][16][17][18] Recent studies, which have focused on gating engineering with graphene, a passivation layer with hexagonal boron nitride or a self-assembled monolayer, and contact engineering with low work-function electrodes, have demonstrated that layered InSe possesses an intrinsically excellent charge transport and optoelectronic performance that are comparable with majority of 2D materials. [19][20][21][22][23][24][25] For instance, Wang Tunability and stability in the electrical properties of 2D semiconductors pave the way for their practical applications in logic devices. A robust layered indium selenide (InSe) field-effect transistor (FET) with superior controlled stability is demonstrated by depositing an indium (In) doping layer. The optimized InSe FETs deliver an unprecedented high electron mobility up to 3700 cm 2 V −1 s −1 at room temperature, which can be retained with 60% after 1 month. Further insight into the evolution of the position of the Fermi level and the microscopic device structure with different In thicknesses demonstrates an enhanced electron-doping behavior at the In/InSe interface. Furthermore, the contact resistance is also improved through the In insertion between InSe and Au electrodes, which coincides with the analysis of the low-frequency noise. The carrier fluctuation is attributed to the dominance of the phonon scattering events, which agrees with the observation of the temperature-dependent mobility. Finally, the flexible functionalities of the logic-circuit applications, for instance, inverter and not-and (NAND)/not-or (NOR) gates, are determined with these surface-doping InSe FETs, which establish a paradigm for 2D-based materials to overcome the bottleneck in the development of electronic devices. InSe TransistorsBecause of the down scaling limit of silicon-based devices, 2D materials with prominent mechanical flexibility and carrier transport performance have provided significant potential for their use in the new generation atomic electronic devices. [1][2][3][4][5][6] Following in the footsteps of the discovery of monolayer

Strong Electron-Phonon Coupling and its Influence on the Transport and Optical Properties of Hole-Doped Single-Layer InSe

“…In all cases we obtain remarkably low values of the order of 1 cm 2 V −1 s −1 . This result is highly unexpected in view of recent experimental reports on high mobility in 2D InSe [1][2][3][4]. We note, however, that our finding is solely applicable to free-standing InSe single Table I with the corresponding conductivity values.…”

A Triode Device with a Gate Controllable Schottky Barrier: Germanium Nanowire Transistors and Their Applications

“…In electronics, noise refers to unwanted or parasitic random perturbations overlying the targeted signals. Because of the scaling requirements for next‐generation integrated circuits, LF noise measurements are used to explore the fluctuation mechanisms arising from either intrinsic trapping processes or contact contributions in solid‐state devices . The typical power spectrum current noise S I is shown as a function of frequency in Figure a with different V ds values.…”

Low‐Voltage Operational, Low‐Power Consuming, and High Sensitive Tactile Switch Based on 2D Layered InSe Tribotronics

“…The band gap of bulk and monolayer InSe ranges from 1.26 to 2.11 eV, so it is photoresponsive from the visible to infrared regions. Several innovative studies have used passivation, specific gating, and surface doping to enhance the carrier transport properties of InSe field‐effect transistors (FETs), revealing their promise for use in logic circuits, memory, and flexible sensors . However, due to the challenge of direct interaction between external environment triggering and the electronic devices, all of the above‐mentioned systems need to consume plenty of power every day, which limits their practical applications.…”