Air Annealing Process for Threshold Voltage Tuning of MoTe2 FET

Abstract

A stable doping technique for modifying the conduction behaviour of two-dimensional (2D) nanomaterial-based transistors is imperative for applications based on low-power complementary oxide thin-film transistors. Achieving an ambipolar feature with a controlled threshold voltage in both the p- and n-regimes is crucial for applying MoTe2-based devices as electronic devices because their native doping states are unipolar. In this study, a simple method to tune the threshold voltage of MoTe2 field-effect transistors (FETs) was investigated in order to realise an enhancement-mode MoTe2 thin-film transistor by implementing a facile method to modulate the carrier polarity based on the oxidative properties of MoTe2 FETs. Annealing in air induced a continuous p-doping effect in the devices without significant electrical degradation. Through a precise control of the duration and temperature of the post-annealing process, the tailoring technique induces hole doping, which results in a remarkable shift in transfer characteristics, thus leading to a charge neutrality point of the devices at zero gate bias. This study demonstrates the considerable potential of air heating as a reliable and economical post-processing method for precisely modifying the threshold voltage and further controlling the doping states of MoTe2-based FETs for use in logic inverters with 2D semiconductors.

Chemical Dopant-Free Controlled MoTe2/MoSe2 Heterostructure toward a Self-Driven Photodetector and Complementary Logic Circuits

“…However, for the annealed sample, two new features are present, which are at 413.0 and 395.5 eV associated with the oxidization state 6 + of Mo like in MoO 3 or MoO X , respectively . Additionally, a clear redshift of the Raman peaks is also observed by comparing annealed and pristine MoTe 2 in Figure S9, indicating that the oxygen doping-dependent lattice vibration also happens in MoTe 2 …”

“…29 Additionally, a clear redshift of the Raman peaks is also observed by comparing annealed and pristine MoTe 2 in Figure S9, indicating that the oxygen doping-dependent lattice vibration also happens in MoTe 2 . 23 To estimate the Schottky barrier height (SBH) at the metal−semiconductor interface before and after annealing, the temperature-dependent transfer curves of MoSe 2 and MoTe 2 FETs are performed in Figure 3 and Figures S10−S13. The effective barrier height (Φ B ) can be extracted from the slope of the linear fit to ln(I D /T 3/2 ) versus 1000/T, according to the thermionic emission theory: 30…”

“…Recently, 2D MoTe 2 , as one of the typical TMDCs, has been proven to possess high-concentration point and line defects with considerable Te vacancies, , making it sensitive to oxygen and water molecules. It is reported that the straightforward thermal annealing in air can easily modulate the electrical transport polarity of the MoTe 2 FET from the intrinsic electron-dominated to hole-dominated properties without any chemical dopants or special gases needed. , Such a simple yet effective doping method provides potential for its functional applications in various fields. However, up to now, related studies are still lacking, and more efforts need to be made.…”

Enhanced contact properties of MoTe2-FET via laser-induced heavy doping

“…[6][7][8] Intrinsic 2H-MoTe 2 always shows ambipolar transfer properties due to its small band gap and can be easily doped to exhibit n-or p-type transfer properties. [9][10][11][12] Therefore, it has excellent potential for applications in complementary MOSFET. [13][14][15] However, the 2D-FET using TMDC materials still presents a significant challenge in contact properties owing to the Fermi level pinning (FLP) effect in the contact interface caused by intrinsic defects and metal deposition.…”