Controllable P‐ and N‐Type Conversion of MoTe₂ via Oxide Interfacial Layer for Logic Circuits

Abstract

To realize basic electronic units such as complementary metal‐oxide‐semiconductor (CMOS) inverters and other logic circuits, the selective and controllable fabrication of p‐ and n‐type transistors with a low Schottky barrier height is highly desirable. Herein, an efficient and nondestructive technique of electron‐charge transfer doping by depositing a thin Al2O3 layer on chemical vapor deposition (CVD)‐grown 2H‐MoTe2 is utilized to tune the doping from p‐ to n‐type. Moreover, a type‐controllable MoTe2 transistor with a low Schottky barrier height is prepared. The selectively converted n‐type MoTe2 transistor from the p‐channel exhibits a maximum on‐state current of 10 µA, with a higher electron mobility of 8.9 cm2 V−1 s−1 at a drain voltage (Vds) of 1 V with a low Schottky barrier height of 28.4 meV. To validate the aforementioned approach, a prototype homogeneous CMOS inverter is fabricated on a CVD‐grown 2H‐MoTe2 single crystal. The proposed inverter exhibits a high DC voltage gain of 9.2 with good dynamic behavior up to a modulation frequency of 1 kHz. The proposed approach may have potential for realizing future 2D transition metal dichalcogenide‐based efficient and ultrafast electronic units with high‐density circuit components under a low‐dimensional regime.

Recent Advances in Ambipolar Transistors for Functional Applications

“…The MoS 2 FET presented extremely large on/off ratio (about 10 8 ) and homogeneous performance within a small region of ≈50 mm 2 in the whole wafer. The inverter exhibited extremely high voltage gain of 60 at V DD = 5 V. Apart from MoS 2 , MoTe 2 has also been extensively investigated to achieve ambipolar carrier conduction as well as high‐performance inverter devices . Lim et al exploited atomic‐layer‐deposition‐generated H‐doping to achieve electron‐dominated α‐MoTe 2 flake with electron mobility of 18 cm 2 V −1 s −1 , which finally gave rise to stable CMOS inverters with large gain value (29) and small static power dissipation on the order of nanowatts .…”

Low‐Power Complementary Inverter with Negative Capacitance 2D Semiconductor Transistors

“…CMOS logic dissipates less static power than transistor‐transistor logic or NMOS logic because of the low static current, and is one of the most used technologies in VLSI chips. [ 5,8,19–21 ] The construction of complementary circuits requires both n‐ and p‐type unipolar FETs. However, most of TMD semiconductors (MoS 2 , WS 2 , etc.)…”

Ambipolar 2D Semiconductors and Emerging Device Applications

“…The ultrathin characteristic of the 2D structures makes them very sensitive to dopants and adsorbates, which can be used to engineer the major charge carriers in 2D semiconductors and thus developed for CMOS circuits. [185,[255][256][257][258][259] With this method, Yu et al realized an air-stable high-performance WSe 2 CMOS inverter with outstanding voltage transfer property, full logic swing, and high noise margin (Figure 7a-g). [260] In their work, the stable P-FET was improved by covering the WSe 2 with tetrafluoro-tetracyanoquinodimethane (F 4 TCNQ) and PMMA mixture film, and the N-type one was passivized with AlOx, both of which were achieved on the same WSe 2 flake.…”

“…[261] Recently, Park et al proposed a prototype homogeneous CMOS PMMA, [221] BV, [222] Cs 2 CO 3 , [255] K, [263] Si x N y [264] Contact Pd [45,109] Ti, [45] Ni [109] MoS 2 Dopant Nb,* [212] P,* [215] AuCl 3 [217,218] BV, [218] K [256] Contact Pt(transferred), [123] Au, [126] Pd [126,160] Mo, [114] Sc, [114] Ti [161] MoSe 2 Dopant Nb* [213] -Contact --WSe 2 Dopant NO 2 , [185] 4-NBD, [253] MoO 3 , [258] F 4 TCNQ-PMMA [260] CTAB, [219] DETA, [253] K, [256,257] AlO x [260] Contact Pd [44,185] Ni, [44] Ag, [183] Ti [185] MoTe 2 Dopant -BV, [254] Al 2 O 3 inverter by depositing Al 2 O 3 film on the CVD-MoTe 2 to convert it from P-type to N-type, offering a possibility for future large scale CMOS circuit applications. [259] BP is expected to be a good candidate for electronic circuits owning to its tunable direct bandgap and high carrier mobility, which is recognized as an ambipolar semiconductor with intrinsic P-type. [22,262] Several efforts have been made on the fabricati...…”

“…The ultrathin characteristic of the 2D structures makes them very sensitive to dopants and adsorbates, which can be used to engineer the major charge carriers in 2D semiconductors and thus developed for CMOS circuits. [ 185,255–259 ] With this method, Yu et al. realized an air‐stable high‐performance WSe 2 CMOS inverter with outstanding voltage transfer property, full logic swing, and high noise margin ( Figure a–g).…”