Comparing Thermal Durability and Effects of Annealing Temperature on Characteristics of Hydrogen-Doped ZnO, AZO, and GZO Thin Films

Abstract

In this work, undoped, aluminum-, and gallium-doped ZnO thin films (ZnO-H, AZO-H, and GZO-H, respectively) deposited on soda-lime glass substrates by magnetron sputtering method in a gas mixture of hydrogen and argon are annealed at various temperatures in the range of 200–500°C in air to evaluate the durability of those films under annealing temperature. From photoluminescence spectra, formation of point defects, especially oxygen vacancies, when hydrogen diffuses out of the films at high annealing temperature is exhibited via a significant increase of visible emissions. We find out that carrier concentration and Hall mobility of AZO-H and ZnO-H films dramatically decrease, while those of GZO-H film are still stable as the annealing temperature increased from 200°C to 300°C. We proposed a model for interpreting the thermal durability of GZO-H film that, at an annealing temperature of 300°C, Ga3+ ions located at adjacent Zn sites can push hydrogen atoms, which are broken out of the antibonding sites which are perpendicular to the c -axis (AB┴), into bond center sites paralleled to the c -axis (BC//). The movement of hydrogen from AB┴ to BC// site also gives rise to the durability of electrical properties of GZO-H films at the high annealing temperature.

Effect of Argon Annealing Treatment on Photoelectric Properties of GZO Films Deposited by Atomic Layer Deposition

“…Ga-doped ZnO (GZO) exhibits significant promise for diverse optoelectronic applications owing to its advantageous characteristics, including high carrier concentration, electrical conductivity, controllable photoelectric properties, and superior photodetection properties compared to pure ZnO. − GZO films have been widely used in various applications, such as LEDs, solar cells (SCs), memristors, and sensors . However, advances in GZO-based devices have been delayed by the complexity of understanding and evaluating the optoelectrical behavior of intrinsic defects such as Ga interstitial (Ga i ), Ga substitute for Zn (Ga Zn ), GaO x suboxides, oxygen vacancy ( V O ), zinc interstitial (Zn i ), zinc vacancy ( V Zn ), and their complexes. , Researchers aimed to manipulate the defects using various approaches.…”