Journal of Physics and Chemistry of Solids 148 (2021) 109706 Available online 14 August 2020 0022-3697/© 2020 Elsevier Ltd. All rights reserved. Improved charge transport properties of graphene incorporated tin oxide based Schottky diode over pure one Pubali Das, Baishakhi Pal, Joydeep Datta, Mrinmay Das, Sayantan Sil, Partha Pratim Ray * Department of Physics, Jadavpur University, Jadavpur, Kolkata, 700032, West Bengal, India A R T I C L E INFO Keywords: rGO-SnO 2 Carrier mobility Schottky diode Rectifcation ratio ABSTRACT Graphene and its nanocomposites with different semiconductor materials have attracted signifcant research interest in the last decade due to their improved performance in various felds. In this report, SnO 2 and a reduced graphene oxide (rGO)-SnO 2 composite is synthesized via hydrothermal method. Structural, optical and electrical characterization of the material is performed. Incorporation of rGO increases the light absorption and reduces the band gap of SnO 2 . Schottky barrier formation at metal-semiconductor junction is important for various appli- cations. Here, we describe the performance of SnO 2 and rGO-SnO 2 based Schottky diode. Important diode pa- rameters like rectifcation ratio, ideality factor, barrier height and series resistances are calculated from forward Current density-voltage (J-V) characteristics. rGO-SnO 2 shows much better performance compared to SnO 2 . Analysis of Photoresponse behavior reveals that rGO-SnO 2 shows photosensitivity of about 9.95 which is higher than that of SnO 2 (2.42). After incorporation of rGO, other diode parameters and transport properties were also improved. To gain better insight on charge transport properties, space charge limited current theory has been utilized. In rGO-SnO 2 , carrier mobility is increased by 62% compared to SnO 2 , implying that rGO-SnO 2 has better charge transport due to enhanced electron hole separation which is attribute to the presence of graphene. 1. Introduction Graphene is a two dimensional material with monolayer honeycomb nanostructure composed of sp 2 hybridized carbon atoms [1]. It has very large surface area (2630 m 2 /g) which facilitates higher absorption of light and greater interfacial contact [2]. It is a very thin but strong material with high carrier mobility and possesses optical transparency of wide wavelength range [3]. Nowadays, with these excellent properties, graphene have become good candidates for uses in different applications such as optoelectronic devices, photosensors, supercapacitors, solar cell etc [4,5]. Graphene has already been used in numerous applications of Schottky diodes which is a key part of many electronic devices [6]. Higher rate of recombination, interface quality, cost and toxicity of the used materials are the issues for Schottky barrier diode (SBD) [7]. To overcome these problems, a number of semiconductor materials have been explored. Graphene based nanocomposite materials are especially attractive choice for improved performance. Nowadays, metal oxide based semiconductors are of great interest due to their versatile prop- erties. They are applied frequently in feld effect transistor, chemical sensors and memory application [8]. Among them SnO 2 is used widely for its low resistivity, excellent electron mobility, non toxicity, good stability, low cost and availability [9]. It has application as gas sensors, anode in lithium ion batteries etc. [10] SnO 2 is an n-type wide band gap semiconductor (bandgap of bulk SnO 2 is 3.6 eV) [11]. So, it is only sensitive to lower light wavelength. Also it has higher recombination rate. If its bandgap and recombination rate can be reduced, we can use it for photovoltaic application and other optoelectronic devices. It has been shown that if graphene is incorporated in the SnO 2 , the light ab- sorption range of SnO 2 can be increased. According to earlier reports, graphene-SnO 2 composite is promising for its effective changes in dielectric properties, gas sensing, supercapacitor, and feld emission study [12]. But investigation of Schottky diode properties through gra- phene-SnO 2 /metal junction has gained rare notice. It motivated us to investigate graphene-SnO 2 based Schottky barrier diode compared to the Schottky barrier diode fabricated with pure SnO 2 , which can be benefcial to understand the effect of graphene on device performance and charge transport properties of the material. As pure graphene is hard to achieve, reduced graphene oxide was used. Graphene oxide (GO) can be produced using a modifed Hummers’ method and after that followed by a reduction procedure GO can be * Corresponding author. Department of Physics, Jadavpur University, Kolkata, 700032, India. E-mail addresses: partha@phys.jdvu.ac.in, parthapray@yahoo.com (P.P. Ray). Contents lists available at ScienceDirect Journal of Physics and Chemistry of Solids journal homepage: http://www.elsevier.com/locate/jpcs https://doi.org/10.1016/j.jpcs.2020.109706 Received 29 April 2020; Received in revised form 27 July 2020; Accepted 9 August 2020