Effects of silicon surface defects on the graphene/silicon Schottky characteristics

Abstract

Distinct characteristics and yet adverse in some cases have been widely reported in the graphene/silicon Schottky junction under DC biasing, for biological and chemical sensing, or as a photodetector. The explanations to these observations are often attributed to the nature of the graphene layer but are still far from satisfactorily for many cases. In this work, we conducted a detailed analysis on both the forward and reverse current-voltage characteristics under different temperatures and we proposed that the silicon surface defects, which had been well-known as Pb0 centers or ≡Si, should play an important role in the adverse characteristics observed in the Gr/Si junction. Compared with the metal/Si and oxide/Si interface, the graphene-isolated Pb0 centers at the Gr/Si interface are chemically inactive but are still electrically active and that modify the carrier transportation over the junction barrier. Without efficient chemical passivation, the graphene-covered Si surface should maintain the most native Si surface such that it preserves a much higher amount of Pb0 centers as compared with other Si junctions or interfaces. This should be the main origin for the reported adverse current-voltage characteristics.

Keywords

• Graphene/silicon Schottky diode
• Temperature dependence
• Silicon dangling bond
• Pb0 centers