Double-exponential current-voltage (I-V) behavior of bilayer graphene-based Schottky diode

Researches on layered materials such as graphene have attracted lots of attention recently. It has been shown that these materials have make a junction with many semiconductor materials that behave like Schottky diodes and have rectifying characteristics. The comprehension of its fabrication process and properties are a critical need toward graphene-based integrated electronics. The purpose of this study is to find out the current-voltage (I-V) performance of Bilayer Graphene (BLGr) based heterostructure fabricated on Al2O3/p-Si, and the effect of BLGr on diode parameters. Graphene has been grown on copper (Cu) foil by Chemical Vapor Deposition (CVD) method and transferred onto Al2O3/p-Si by using the polymethyl methacrylate (PMMA) wet transfer method. Raman analysis has been performed to obtain supportive information about CVD synthesized graphene film. The I-V plot of the diode exhibited two linear regions named Region 1 (0.08-0.19 V) and Region 2 (0.21-0.40 V). The double-exponential I-V behavior of the diode has been analyzed. The diode characteristics such as barrier height (phi(B0)), series resistance (R-s), and ideality factor (n) have been calculated by using thermionic emission (TE), Norde, and Cheung methods. Especially, the values of the barrier height were compared with one another. It was found that they are in good agreement. Additionally, current conduction mechanisms of the diode were investigated using the forward bias ln(I) versus ln (V) plot. At lower and higher forward bias regions, the conduction mechanisms were determined as ohmic behavior and trap charge limiting current mechanism (TCLC), respectively.