Fabrication and characterization of reduced graphene oxide/silicon back-to-back schottky diode

Graphene-based back-to-back Schottky diode (BBSD) is a simple device yet possesses promising attributes for applications such as chemical sensor and photodetector. Nevertheless, experimental work on graphene BBSD is relatively limited, where most of the works utilized graphene made from chemical vapor deposition and epitaxial growth. This work investigated the possibility of fabricating the BBSD using low-cost reduced graphene oxide (rGO) and simple fabrication techniques, namely vacuum filtration and chemical reduction via ascorbic acid. Understanding the capability and limitation of these fabrication techniques is important before they can be employed. Formation of graphene oxide (GO) thin film via vacuum filtration with different GO dispersion volume (50, 100, 150 and 200 ml) and concentration (0.4, 0.8, 1.0 ppm) were investigated. Thin films morphology and thickness were characterized using atomic force microscopy. The GO film thickness could be controlled from 30 to 160 nm by varying dispersion volume and concentration. As for reduction process, the correlation between reduction degree with reduction parameters, namely ascorbic acid concentration, duration and process sequence, were analyzed. The reduction degree was assessed by means of Raman spectroscopy and sheet resistance measurement. The lowest sheet resistance at 3.58 MΩ/sq was obtained for rGO film reduced before and after film transfer using 13.6 mg/ml ascorbic acid for 12 hours. Based on the result from vacuum filtration and chemical reduction processes, an rGO/silicon BBSD device was fabricated. The fabricated device was characterized by current-voltage measurement at different temperatures. A nonlinear curve was observed indicating the formation of double Schottky barrier at rGO/silicon junction. Barrier height, ideality factor and series resistance were extracted directly from the measured characteristics. The barrier height inhomogeneity was also assessed. The rGO/Si junction has average barrier height of 1.26 eV with standard deviation of 0.167 eV. In conclusion, the result from this work confirmed the feasibility of fabricating rGO BBSD using a low-cost graphene derivatives and fabrication technique. This is favorable towards mass production of graphene-based chemical sensor and photodetector

Back-to-back schottky diode from vacuum filtered and chemically reduced graphene oxide

This paper presents fabrication of reduced graphene oxide (rGO)/silicon (Si) back-to-back Schottky diode (BBSD) through graphene oxide (GO) thin film formation by vacuum filtration and chemical reduction of the film via ascorbic acid. In order to understand and assess the viability of these two processes, process condition and parameters were varied and analyzed. It was confirmed that the GO film thickness could be controlled by changing GO dispersion volume and concentration. Filtration of 200 ml of 0.4 ppm GO dispersion produced average film thickness of 53 nm. As for the reduction process, long duration was required to produce higher reduction degree. rGO film that underwent two times reduction at before and after transfer process with concentrated ascorbic acid gave the lowest sheet resistance of 3.58 MΩ/sq. In the final part of the paper, result of the BBSD device fabrication and current-voltage characterization were shown. The formed two rGO/Si Schottky junctions in the BBSD gave barrier height of 0.63 and 0.7 eV. The presented results confirmed the viability of fabricating rGO-based device using a simple method and without requirement of sophisticated equipment

Junction properties analysis of silicon back-to-back Schottky diode with reduced graphene oxide Schottky electrodes

Reduced graphene oxide (rGO)/silicon (Si) Schottky junction possesses promising attributes for various applications such as chemical sensor and photodetector. In this paper, a fabrication of simple back-to-back rGO/Si Schottky junction structure is presented. The device was fabricated via wet processes such as vacuum filtration, patterning by delamination, wet transfer and chemical reduction by ascorbic acid. From the current-voltage measurement, series resistance, barrier height and ideality factor were investigated at different temperature. Barrier height increases and ideality factor decreases with the increase of temperature indicating the inhomogeneity of the junction interface. By considering the Gaussian distribution of barrier height, the fabricated Schottky junction was shown to possess the mean barrier height of 1.24 eV with standard deviation value of 0.16 eV. The obtained mean barrier height was larger than the bandgap of Si, indicating the presence of thin insulation layer at the interface