Improving the Performance of Graphene Phototransistors Using a Heterostructure as the Light-Absorbing Layer

Abstract

Interfacing light-sensitive semiconductors with graphene can afford high-gain phototransistors by the multiplication effect of carriers in the semiconductor layer. So far, most devices consist of one semiconductor light-absorbing layer, where the lack of internal built-in field can strongly reduce the quantum efficiency and bandwidth. Here, we demonstrate a much improved graphene phototransistor performances using an epitaxial organic heterostructure composed of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and pentacene as the light-absorbing layer. Compared with single light-absorbing material, the responsivity and response time can be simultaneously improved by 1 and 2 orders of magnitude over a broad band of 400-700 nm, under otherwise the same experimental conditions. As a result, the external quantum efficiency increases by over 800 times. Furthermore, the response time of the heterostructured phototransistor is highly gate-tunable down to sub-30 μs, which is among the fastest in the sensitized graphene phototransistors interfacing with electrically passive light-absorbing semiconductors. We show that the improvement is dominated by the efficient electron-hole pair dissociation due to interfacial built-in field rather than bulk absorption. The structure demonstrated here can be extended to many other organic and inorganic semiconductors, which opens new possibilities for high-performance graphene-based optoelectronics.

Ultrahigh Stability 3D TI Bi2Se3/MoO3 Thin Film Heterojunction Infrared Photodetector at Optical Communication Waveband

“…Figure S1 of the Supporting Information demonstrates the manufacturing process of Bi 2 Se 3 /MoO 3 thin film heterojunction photodetector. Generally speaking, the quality of the prepared thin film will affect the properties of thin film photodetectors . MoO 3 thin films were prepared by thermal evaporation and postgrowth anneal.…”

“…Then when the illumination photon energy exceeds MoO 3 and below Bi 2 Se 3 , e.g., 1310 nm, at this point MoO 3 possesses basically no absorption capacity. Therefore, the photocurrent above this region should be mainly provided by Bi 2 Se 3 . The device is measured by pulse signal switching incident laser every 1 s at V bias of 20 V from 405 to 1550 nm (Figure 2c).…”

Toward High‐Performance Photodetectors Based on 2D Materials: Strategy on Methods

“…Organic molecules can also be used as photon‐absorbing materials . As shown in Figure g, a dye‐sensitized MoS 2 photodetector has been reported, which consists of monolayer MoS 2 treated with rhodamine 6G (R6G) organic‐dye molecules with an optical bandgap of 2.38 eV.…”

Broadband Optical‐Fiber‐Compatible Photodetector Based on a Graphene‐MoS2‐WS2 Heterostructure with a Synergetic Photogenerating Mechanism

“…[5][6][7][8][9][10] However, for photo detection applications, individual 2D materials do not possess sufficiently high responsivity (R), fast response time (τ), and broadband working bandwidth simultane ously. [14,15] Considering the high carrier mobility inside graphene, [16,17] an effective method of building highperformance photodetectors is to interface gra phene with lightabsorbing materials, such as quantum dots, [18] perovskites, [19] TMDCs, [20] organic heterostructure, [21,22] sil icon, [23] etc. [8,[11][12][13] Photo detectors based on molybdenum disulfide (MoS 2 ) show a high photoresponsivity of ≈880 A·W −1 , but their response time is rel atively long due to the long life time of their photocarriers, and their working wave length is limited to the visible spectrum due to the large bandgap of MoS 2 .…”