Effects of AZO film as inductive layer and annealing temperature on microstructure crystallinity and electrical and optical properties of IGZO/SiO2 and IGZO/AZO/SiO2 specimens

In the present study, annealing at three temperatures (800, 900, and 1000 degrees C) is applied to indium gallium zinc oxide (IGZO)/SiO2 specimens to investigate the effect of annealing temperature on amorphous IGZO (a-IGZO) crystallization. Then, IGZO/AZO/SiO2 specimens are prepared and annealed at 1000 degrees C to evaluate the effect of an Al-doped ZnO (AZO) film inserted between IGZO and an a-SiO2 substrate on a-IGZO crystallization to IGZO. The effects of annealing temperature and the AZO film on microstructure crystallization and optical and electrical properties are evaluated. The intensity of the X-ray diffraction peaks of crystalline IGZO increased with increasing annealing temperature. The insertion of the AZO film induced a-IGZO crystallization, which led to comparatively higher peak intensities for the IGZO/AZO/SiO2 specimen annealed at 1000 degrees C. The use of AZO film changed the In3+ hexagonal structure of the IGZO/SiO2 specimen with unequal bond lengths into the regular hexagonal structure of the IGZO/AZO/SiO2 specimens. Increasing the annealing temperature from 800 to 1000 degrees C slightly reduced (similar to 0.09%) the transmittance of the IGZO/SiO2 specimens. The microstructure transformation due to AZO addition made the transmittance of the IGZO/AZO/SiO2 specimen annealed at 1000 degrees C only 1.46% lower than that of the IGZO/SiO2 specimen. A sufficiently high annealing temperature and/or the use of AZO film increases carrier concentration and mobility and decreases resistivity and band gap. AZO film can be used to induce the crystallization of a-IGZO to efficiently improve electrical properties without a significant loss in transmittance.