Space-confined solid-phase growth of two-domain 1T′-ReSe2 for tunable optoelectronics

Abstract

Two-dimensional layered ReX2 (X = Se, S) has attracted researcher's great interest due to its unusual in-plane anisotropic optical and electrical properties and great potential in polarization-sensitive optoelectronic devices, while the clean, energy-saving, and ecological synthesis of highly crystalline ReSe2 with controlled domains remains challenging. Here, we develop a space-confined solid-phase approach for growing high-quality two-domain 1T′-ReSe2 with tunable optoelectronic properties by using pure Re powder as a Re precursor. The results show that ReSe2 can be grown at a temperature as low as 550 °C in a small-tube-assisted space-confined reactor, with its size and shape well-tailored via temperature control. A solid-phase two-domain ReSe2 growth mechanism is proposed, as evidenced by combining in situ optical monitoring, ex situ electron microscope, elemental mapping, and polarized optical imaging. Moreover, two-domain ReSe2 transistors are fabricated, which exhibit a switchable transport behavior between n-type and ambipolar character via grain boundary orientation control. This modulation phenomenon is attributed to the different doping levels between grain boundary and single domain. Furthermore, our two-domain ReSe2 photodetectors exhibit a highly gate-tunable current on–off ratio (with a maximum value of ∼8.2 × 103), a polarization-sensitive photo-response, and a high-speed response time (∼300 μs), exceeding most of the previously reported ReX2 photodetectors. Our work, thus, provides a low-consumption, energy-saving growth strategy toward high-quality, domain-controlled ReX2 for highly tunable and high-performance optoelectronics.