Thermal Dissipation Annealing for Crystallization of In‐Doped ZnO Films Deposited on Polyethylene Naphthalate Substrate without Substrate Deformation

Abstract

High‐temperature annealing is essential to crystallize sol–gel spin‐coated ZnO films but is a critical disadvantage in manufacturing flexible and transparent electronics, owing to low thermal stability of polymer substrates. Thus, a novel annealing method, named thermal dissipation annealing (TDA), is developed. TDA method can anneal ZnO films without any deformation of polymer substrates. The effects of TDA method are confirmed by annealing ZnO films deposited on glass and polyethylene naphthalate substrates. Moreover, In‐doped ZnO (IZO) films are annealed by TDA method, and the properties of IZO films are investigated. ZnO films annealed by TDA method show graphene‐like nanosheets and exhibit much higher photosensitivity than ZnO films annealed by furnace or infrared (IR) lamp. For IZO films annealed by TDA method, entangled nanosheets begin to unravel with increasing doping concentration, and size of nanosheets significantly decreases at 0.04 at%. The photosensitivity of the IZO films decreases from 21.77 to 2.76 with increasing doping concentration. Therefore, flexible and transparent UV photodetectors based on sol–gel spin‐coated ZnO films can be fabricated through TDA method; however, when ZnO films annealed by TDA method are utilized to UV photodetectors, In dopant is not a suitable material to improve the performance of UV photodetectors.