Interdigitated electrodes enhanced photosensitive monolayer WS2 field effect transistor on glass substrate

Recently, 2D-material-based optoelectronic devices are integrated on optical-fiber as a substrate. However, silicon substrate, usually for optoelectronic device integration, impedes fiber-optic integration due to its much larger refractive index. Here, we fabricated a highly transparent photosensitive field effect transistor (FET) using monolayer WS2 on a fiber-compatible glass substrate with interdigitated electrodes. Experiments shows that the current switching ratio for the FET reach up to 105. Additionally, the interdigitated electrodes could improve photocurrent collection capability, leading to a relative high responsivity of 1.48 mA/W. Meanwhile, the difference in the photocurrent induced by light illumination from the front and back to the device is only 1.25%. This indicates light beam can pass through the device, facilitating online monitoring of optical power. Moreover, it is also shown that the transmitted light beam could be reflected to retransmit thought the device, thus increasing photocurrent by 6.8%. Such glass-substrate provide a simple and feasible strategy for future incorporation of optical-fiber with on-chip device.