Horizontally-connected ZnO-graphene hybrid films for multifunctional devices

Abstract

Here we designed horizontally-connected ZnO thin films and graphene in order to combine advantages of ZnO thin films, which are high on/off ratio and photo responsivity, and the superior mobility and sensitivity of graphene for applications in thin film transistors (TFTs) and flexible photodetectors. To synthesize the ZnO/graphene hybrid films, a 70-nm-thick ZnO thin film with a uniformly flat surface deposited by the atomic layer deposition process was horizontally connected with highly crystalline monolayer graphene grown by thermal chemical vapor deposition. The photocurrent on-off ratio, response time, and recovery time of the hybrid photodetectors were estimated to be 102, 34s, and 27s, respectively. The photocurrent from the hybrid photodetector decreased only by two-fold, whereas a significant decrease in photocurrent by two orders of magnitude was observed from the ZnO thin film based photodetectors after 105 cycles of 5-mm radius bending. The hybrid TFT exhibited unipolar n-channel transistor behavior with electron mobility of 68.7cm2/Vs and on-off ratio of 107.