Monolayer MoSe₂ Grown by Chemical Vapor Deposition for Fast Photodetection

Abstract

Monolayer molybdenum disulfide (MoS 2 ) has become a promising building block in optoelectronics for its high photosensitivity. However, sulfur vacancies and other defects significantly affect the electrical and optoelectronic properties of monolayer MoS 2 devices. Here, highly crystalline molybdenum diselenide (MoSe 2 ) monolayers have been successfully synthesized by the chemical vapor deposition (CVD) method. Low-temperature photoluminescence comparison for MoS 2 and MoSe 2 monolayers reveals that the MoSe 2 monolayer shows a much weaker bound exciton peak; hence, the phototransistor based on MoSe 2 presents a much faster response time (<25 ms) than the corresponding 30 s for the CVD MoS 2 monolayer at room temperature in ambient conditions. The images obtained from transmission electron microscopy indicate that the MoSe exhibits fewer defects than MoS 2 . This work provides the fundamental understanding for the differences in optoelectronic behaviors between MoSe 2 and MoS 2 and is useful for guiding future designs in 2D material-based optoelectronic devices.

Chemical Vapor Deposition of High‐Quality Large‐Sized MoS2 Crystals on Silicon Dioxide Substrates

“…3 cm −1 respectively 40, 41. The PL spectra (inset) shows the characteristic emission peaks corresponding to the emission of MoSe 2 (≈794 nm) and WS 2 (≈632 nm) monolayer 42, 43. These results indicate that these crystals are monolayer crystals with perfect optical properties.…”

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

“…CVD‐grown graphene has made great breakthrough in the growth of large‐area graphene 17, 155, 156, 157, 158, 159, 160. Recently, the synthesis of 2DLMs via CVD methods has been illustrated in many reports especially for MoS 2 ,30, 31, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185 which also shows promising applications in electronics and optoelectronics. Up to now, there are several reports on synthesizing 2D GIVMCs nanoflakes via CVD method, which is still at the initial stage.…”

Ultrafast, Broadband Photodetector Based on MoSe2/Silicon Heterojunction with Vertically Standing Layered Structure Using Graphene as Transparent Electrode

“…To date, a few works have been reported for the photodetectors based on mono‐/multilayer MoSe 2 nanosheets 43, 44, 45. Although they show outstanding device characteristics such as remarkable light response, their response speed (15 ms–8 s) remains too low to meet the requirements for practical applications, and broadband light detection is yet to be demonstrated 43, 44, 45.…”

“…Although they show outstanding device characteristics such as remarkable light response, their response speed (15 ms–8 s) remains too low to meet the requirements for practical applications, and broadband light detection is yet to be demonstrated 43, 44, 45. In conventional photodetectors, diode structure with vertical p–n junctions are normally adopted.…”

“…Significantly, the Gr/MoSe 2 /Si heterojunction photodetector exhibited a wide photoresponse range of 350–1310 nm and an extremely fast response speed of ≈270 ns, which represent the best values reported thus far for MoSe 2 or MoS 2 based photodetectors ( Table 1 ). 43, 44, 45, 51, 52, 53, 54 It is expected that the MoSe 2 /Si heterojunctions will have important applications for high‐performance optoelectronic devices.…”