Advanced Materials: TechConnect Briefs 2015Advanced Materials TechConnect Briefs 2015

Carbon Nano Structures & Devices Chapter 3

Graphene-Based Nanostructures for Advanced Sensing Applications

A. Abdul-Wahed, and M. Serry
The American University in Cairo, Egypt

pp. 148 - 151

Keywords: graphene, Schottky diode, nanosensors

New nanostructured Schottky junctions based on graphene/platinum grown on different substrates are fabricated and investigated. The integration of graphene layer (s) on regular M-S junctions was only possible by using an ALD grown platinum thin film (~40 nm) and then growing graphene in PECVD at temperatures lower than platinum silicide formation temperature (i.e., < 700 °C). The electrochemical and radiation sensing behaviors were investigated using two different substrate types. The first is a moderately doped n-type (e− conc. ≈ 2 × 1015 cm−3) silicon substrate in which a Schottky rectifier response with different threshold voltages was observed. In case of using high resistivity silicon substrates ( ) an order of magnitude increase in the generated current was observed. In the case of adding a dielectric layer to form a graphene-metal-insulator-semiconductor junction (Graphene−MIS) a linear ohmic response was observed. The obtained responses were explained by studying the band diagrams for the different with the aid of XPS and Raman analyses which have clearly indicated the p-doping of the graphene layer in response to γ-ray radiations, which resulted in a strong reversed current tunneled through the ultrathin platinum layer.