Roughness of ZnS : Pr,Ce/Ta2O5 interface and its effects on electrical performance of alternating current thin-film electroluminescent devices

Roughness effects of neighboring dielectrics on electrical characteristics of thin-film electroluminescent devices were investigated in order to impro ve the understanding of physics for the devices. Atomic force microscopy an alysis reveal that thicker bottom layer of Ta2O5 shows rougher surface resu lting in the rougher surface of ZnS:Pr,Ce layer, It can be easily seen that the de leakage current increases rapidly with increase of surface roughnes s Furthermore, it is notable that the initiation field of Poole-Frenkel cur rent conduction is lowered by increasing surface roughness of Ta2O5 thin fi lm. Internal charge-phosphor field (Q(int) - F-p) analysis and capacitance- ac voltage (C-V) analysis for ITO-Ta2O5-ZnS: Pr,Ce-Al and ITO-Ta2O5ZnS:Pr,C e-Ta2O5-Al show that the steady state phosphor field is smaller and C-V cur ve in transition region is less steep with increase of root-mean-square rou ghness between lower dielectric and phosphor layer in the alternating curre nt thin-film electroluminescent (ACTFEL) devices. Therefore, we conclude th at interface roughness is one of the physical factors to change the electri cal performance of ACTFEL device.