Analysis of electrical properties of graphene–ZnO/n-Si(111) Schottky contact

In this article, the graphene (G)–ZnO composite films was prepared on the surface of n-Si(111) substrate by sol–gel method for the formation of G–ZnO/n-Si(111) Schottky contact. The results show that the growth direction of ZnO films can be changed from (002) to (101) by adding G, and the surface roughness of ZnO films can be reduced. By the means of current–voltage (I–V) measurements, it is observed that barrier height values increased and ideality factor decreased with the increasing of G content, indicating that G can significantly improve the rectifying characteristics of ZnO/n-Si (111) Schottky contacts. This phenomenon is mainly due to the reduction of oxygen vacancies in ZnO thin films by adding G. Meanwhile, the barrier height calculated by capacitance–voltage (C–V) method is higher than I–V method, which may be due to the existence of an interface layer or the effect of the image force.