Study on the interface electronic structure, strain modulation and transport properties of composite heterojunction of 2D semimetal TiS2 and MX2 (M=Mo, W, Cr, Zr, Hf; X=S, Se, Te) semiconductor

Ohmic contacts play a crucial role in realizing high-performance electronic devices based on two-dimensional materials. The contact between semimetals and semiconductors can mitigate the formation of metal-induced gap states (MIGS), thereby reducing the SBH, enhancing the efficiency of high charge injection, and facilitating the establishment of ohmic contacts. This study involves a systematic exploration of the contact characteristics between the two-dimensional semimetal TiS₂ and semiconductor MX₂ (M = Mo, W, Cr, Zr, Hf; X = S, Se, Te) through first-principles calculations. It is found that the TiS₂/MoSe₂ and TiS₂/WSe₂ heterojunction achieve ohmic contact. Investigations into their transport properties reveal that significant currents can be observed at relatively low voltages, indicating excellent transport performance of these heterojunctions. The TiS₂/CrSe₂ and TiS₂/HfSe₂ contact heterojunctions also show low Schottky barrier height (SBH), with the barrier height being adjustable under strain. The SBH of TiS₂/CrSe₂ and TiS₂/HfSe₂ heterojunctions are very close to zero under stresses of 4 % and −4%, respectively. This also implies that our research can offer valuable guidance for the development of adjustable Schottky nano-devices and high-performance optoelectronic devices.