Hexagonal MoTe2 with Amorphous BN Passivation Layer for Improved Oxidation Resistance and Endurance of 2D Field Effect Transistors

Abstract

Environmental and thermal stability of two-dimensional (2D) transition metal dichalcogenides (TMDs) remains a fundamental challenge towards enabling robust electronic devices. Few-layer 2H-MoTe2 with an amorphous boron nitride (a-BN) covering layer was synthesized as a channel for back-gated field effect transistors (FET) and compared to uncovered MoTe2. A systematic approach was taken to understand the effects of heat treatment in air on the performance of FET devices. Atmospheric oxygen was shown to negatively affect uncoated MoTe2 devices while BN-covered FETs showed considerably enhanced chemical and electronic characteristic stability. Uncapped MoTe2 FET devices, which were heated in air for one minute, showed a polarity switch from n- to p-type at 150 °C, while BN-MoTe2 devices switched only after 200 °C of heat treatment. Time-dependent experiments at 100 °C showed that uncapped MoTe2 samples exhibited the polarity switch after 15 min of heat treatment while the BN-capped device maintained its n-type conductivity for the maximum 60 min duration of the experiment. X-ray photoelectron spectroscopy (XPS) analysis suggests that oxygen incorporation into MoTe2 was the primary doping mechanism for the polarity switch. This work demonstrates the effectiveness of an a-BN capping layer in preserving few-layer MoTe2 material quality and controlling its conductivity type at elevated temperatures in an atmospheric environment.

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

“…It is worth to mention here that for the encapsulation of p‐FETs, the oxide‐based dielectrics are not very favorable candidates which can bring oxygen atoms at the MoTe 2 surface and consequently can contribute in altering the FET performance. In contrast, nonoxide based, environmentally stable materials such as boron nitride could be a more suitable dielectric counterpart for packaging to achieve the long‐term and stable p‐FET operation in MoTe 2 transistors …”

Confined van der Waals Epitaxial Growth of Two-Dimensional Large Single-Crystal In 2 Se 3 for Flexible Broadband Photodetectors

“…First, In 2 Se 3 has a direct bandgap of 1.36 eV [20], which is close to that of silicon (1.10 eV). Second, although some monolayer TMDCs like MoTe 2 also have a direct bandgap of 1.10 eV, they become indirect bandgap materials as the number of layers increases [21], while In 2 Se 3 is a direct bandgap material regardless of its thickness [22, 23]. Third, unlike black phosphorus which is also a direct bandgap 2D material, thin In 2 Se 3 flakes are very stable in air, which is very important for practical applications.…”

Novel strategies for chemical vapor deposition growth and engineering of two-dimensional materials

“…Hence, the presence of B [233][234][235] The presence of oxide components in the XPS spectra indicates that the surface of the MoTe2 is slightly oxidized due to its air-sensitive properties upon exposure to air. [236][237][238][239] The extracted atomic ratio of Mo to Te was 1:2.2, in good agreement to the ideal stoichiometry of MoTe2.…”