Homogeneous 2D MoTe₂ p–n Junctions and CMOS Inverters formed by Atomic‐Layer‐Deposition‐Induced Doping

Abstract

Recently, α-MoTe , a 2D transition-metal dichalcogenide (TMD), has shown outstanding properties, aiming at future electronic devices. Such TMD structures without surface dangling bonds make the 2D α-MoTe a more favorable candidate than conventional 3D Si on the scale of a few nanometers. The bandgap of thin α-MoTe appears close to that of Si and is quite smaller than those of other typical TMD semiconductors. Even though there have been a few attempts to control the charge-carrier polarity of MoTe , functional devices such as p-n junction or complementary metal-oxide-semiconductor (CMOS) inverters have not been reported. Here, we demonstrate a 2D CMOS inverter and p-n junction diode in a single α-MoTe nanosheet by a straightforward selective doping technique. In a single α-MoTe flake, an initially p-doped channel is selectively converted to an n-doped region with high electron mobility of 18 cm V s by atomic-layer-deposition-induced H-doping. The ultrathin CMOS inverter exhibits a high DC voltage gain of 29, an AC gain of 18 at 1 kHz, and a low static power consumption of a few nanowatts. The results show a great potential of α-MoTe for future electronic devices based on 2D semiconducting materials.

Carrier Modulation of Ambipolar Few‐Layer MoTe2 Transistors by MgO Surface Charge Transfer Doping

“…Here, we showed that another candidate doping material, MgO, which is proven air stable and has been used as an effective insert layer for controlling the Schottky barrier height between Co contacts and MoS 2 , is an excellent n‐type surface dopant for MoTe 2 FETs. Worth to emphasis here, very few reported works could achieve the reverse doping of TMDs, tuning the carrier conduction type from n‐type to p‐type or vice versa. Surprisingly, our results demonstrated here successfully showed that by carefully adjusting the thickness of MgO film and the number of MoTe 2 layers it is possible to switch the conduction type of few‐layer MoTe 2 FETs from p‐type to n‐type.…”

Fully Transparent p‐MoTe2 2D Transistors Using Ultrathin MoOx/Pt Contact Media for Indium‐Tin‐Oxide Source/Drain

“…Bulk hexagonal‐structured 2H MoTe 2 has a bandgap of 0.88 eV while one monolayer demonstrates a direct optical bandgap of 1.1 eV, which is overall quite close to the bandgap of Si. p‐type conduction in 2H MoTe 2 is known to be readily achievable using a deep work function metal, Pt for S/D contact . For S/D contact, we sequentially introduce 60 s short O 2 plasma and ultrathin Pt‐deposition processes on MoTe 2 surface before ITO thin film deposition and patterning.…”

Ultrahigh‐Sensitive Broadband Photodetectors Based on Dielectric Shielded MoTe2/Graphene/SnS2 p–g–n Junctions

“…MoTe 2 is a p‐type semiconductor with the 2H structure (trigonal prismatic) and a bandgap of ≈1.0 eV while SnS 2 is an n‐type semiconductor with a bandgap of ≈2.2 eV. Therefore, MoTe 2 and SnS 2 are particular suitable candidates for broadband vdW p–n heterojunction optoelectronics due to their high carrier mobility, complementary bandgaps and chemical stability . Furthermore, the introduction of a graphene‐interlayer in the vdW p–g–n junction may improve the contact between the TMD layers to facilitate electron transport for higher R i and to reduce the interface charge traps for faster photoresponse .…”