Fabrication and current-voltage characteristics of ZnO/α NPD based inorganic-organic hybrid structure

摘要

A transparent inorganic-organic semiconductor heterojunction has been fabricated using a N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,l'biphenyl-4,4diamine (α-NPD) small molecule p-type organic material and n-ZnO. The p-type α-NPD has been deposited by high vacuum resistive thermal evaporation technique on a sputter-deposited ZnO film. The device shows diode-like characteristics with a rectification ratio of ～2. The α-NPD/ZnO interface was modified by introducing a self-assembled monolayer of 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyano-quinodimethane (F_4-TCNQ) on the ZnO surface before the deposition of α-NPD. This improves the rectification ratio of the device almost by 100 times. The introduction of the F_4-TCNQ layer changes the ideality factor from 8.7 to 3.1 and the estimated barrier height value from 0.939 eV to 0.802 eV.