Microscopic Identification of Hot Spots in Multibarrier Schottky Contacts on Pulsed Laser Deposition Grown Zinc Oxide Thin Films

Multiple barriers have been observed in the I- V characteristics of various Schottky diodes (SDs). Here, multibarrier PdOx/ZnO Schottky contacts (SCs) exhibiting three different discrete barrier heights are investigated. Using a model considering three parallel connected SDs with individual barrier potential, ideality factor, and active area, the forward current-voltage characteristic of the PdOx/ZnO SC was accurately modeled. Regions of low barrier height are visualized by dark lock-in thermography as a function of forward current. The microscopic origin of local patches with the lowest barrier height has been identified as incorporation of Al₂O₃ particles affecting the morphological and structural thin film properties on the micrometer scale.