High‐Sensitivity Floating‐Gate Phototransistors Based on WS₂ and MoS₂

Abstract

In recent years, 2D layered materials have been considered as promising photon absorption channel media for next‐generation phototransistors due to their atomic thickness, easily tailored single‐crystal van der Waals heterostructures, ultrafast optoelectronic characteristics, and broadband photon absorption. However, the photosensitivity obtained from such devices, even under a large bias voltage, is still unsatisfactory until now. In this paper, high‐sensitivity phototransistors based on WS2 and MoS2 are proposed, designed, and fabricated with gold nanoparticles (AuNPs) embedded in the gate dielectric. These AuNPs, located between the tunneling and blocking dielectric, are found to enable efficient electron trapping in order to strongly suppress dark current. Ultralow dark current (10−11 A), high photoresponsivity (1090 A W−1), and high detectivity (3.5 × 1011 Jones) are obtained for the WS2 devices under a low source/drain and a zero gate voltage at a wavelength of 520 nm. These results demonstrate that the floating‐gate memory structure is an effective configuration to achieve high‐performance 2D electronic/optoelectronic devices.

WSe2 Photovoltaic Device Based on Intramolecular p–n Junction

“…Consequently, shortening the channel and improving the carrier mobility are effective ways to further decrease the rising time in our device. On the other hand, the rising time, for other 2DLMs‐based photodetectors with in‐plane channels, are reported to be on the scale of tens or hundreds of microseconds . Comparing with them, the τ r = 200 µs achieved by our device shows improvements which is attributed to the p–n junction that separates photoinduced carriers rapidly.…”

“…In recent years, with great optoelectronic performances, 2D layered materials (2DLMs) have been selected as candidate materials for next‐generation photoconductive and photovoltaic devices . An ultrahigh responsivity phototransistor based on MoS 2 channel, has been realized by ferroelectrics .…”

Ultrathin MoO2 nanosheets with good thermal stability and high conductivity

“…Our In recent years, 2D materials have aroused great interest as potential building blocks for a variety of fundamental optoelectronic components. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] To date, various 2D materials have been synthesized, including well-known graphene, 15 transition metal dichalcogenides, 16 antimonene, 17 black phosphorus, 18 Mo 2 C, 19 BN, 20 and so on, but some of which face very challenging in various optical and electronic applications due to zero-bandgap, low conductivity, or severe instability in air. In order to address this problem, it is urgent to develop a new material with a good stability and high conductivity.…”

Design strategies for two‐dimensional material photodetectors to enhance device performance

“…The floating‐gate structure shows infinite potential in ultra‐weak light detection. Recently, the floating‐gate based phototransistors have arisen prominent interest of researchers . By inducing weak photo‐generated carriers trapping in floating‐gate, the 2D materials channel current can be effectively modulated.…”