High performance photodetectors constructed on atomically thin few-layer MoSe2 synthesized using atomic layer deposition and a chemical vapor deposition chamber

Abstract

Two-dimensional (2D) atomic layered transition metal dichalcogenides are promising candidates for use in next generation optoelectronics. However, the low responsivity observed in monolayer MoSe2 photodetectors (PDs) requires strategies to enhance photoelectric performance. Here, we introduce a method to produce few-layer MoSe2 with large continuous area for high-performance optoelectronic devices, using atomic layer deposition (ALD) and a chemical vapor deposition (CVD) chamber. The as-synthesized ultrathin MoSe2 films were characterized by atomic force microscopy (AFM) and transmission electron microscopy (TEM), revealing six polycrystalline layers of hexagonal structure and with an interlayer spacing of 0.66 nm. Few-layer MoSe2 metal-semiconductor-metal (MSM) PDs were prepared with different optically active areas. The PD with a finger spacing of 5 μm exhibited remarkable performance with responsivity, response time, and detectivity of 859 mA/W, 38 ms, and 1.55 × 1011 jones, respectively, making these PDs significantly superior to most previously described MoSe2 PDs and many other 2D semiconductors devices. The use of large-area films and the facile fabrication process described here present a viable route to mass production, opening avenues to develop atomically thin MoSe2 PDs for industrial applications.