PEDOT:PSS/ZnO heterojunctions: resistive switching behavior in memory devices

Abstract

The advancement of hetero-structured ReRAM devices has received increasing attention in the field of optoelectronic applications. In the past few years, zinc oxide (ZnO), an II–VI group semiconductor, has garnered significant interest for ReRAM applications. The present study focuses on the fabrication of bilayers (p–n junction-based ReRAM devices) using n-type ZnO and p-type PEDOT:PSS layer. Using the spray pyrolysis technique, ZnO thin-film layers were formed onto glass substrate. The PEDOT:PSS layers were formed by the spin coating method. The prepared PEDOT:PSS and ZnO bilayers were analyzed by XRD, FESEM, and Raman spectroscopic analysis. The structural analysis of ZnO thin-film layers confirms the presence of the wurtzite phase, highlighting their crystalline nature. Cross-sectional morphological studies demonstrate that all layers are uniformly and distinctly formed, ensuring high-quality formation. The PEDOT:PSS and ZnO thin-film layers were formed onto the ITO substrate, which was sandwiched between the bottom ITO and top (Ag) electrodes. The current–voltage (I–V) characteristics and double logarithmic I–V plots of the fabricated PEDOT:PSS/ZnO heterojunction devices were analyzed for their suitability in ReRAM applications. The results indicate that the devices exhibit bipolar resistive switching behavior, with the conduction mechanism primarily governed by the formation and rupture of conductive filaments (CFs) within the switching layers.