Comparative Study of Thermal Stability of Transparent Conducting ITO/Ag/ITO and IGZO/Ag/IGZO Three-Layer Structures

Transparent conducting three-layer oxide/silver/oxide structures, in which wide-bandgap semiconductor materials ITO and IGZO were used as oxide top and bottom layers, were obtained by the rf magnetron sputtering method. Comparative studies of the morphology, microstructure, optical transmittance, and surface resistance of the obtained three-layer structures were carried out. It was shown that the IGZO/Ag/IGZO structure is characterized by higher optical transmittance in the visible spectral range (T_av = 75.7%) and lower surface resistance (R_surf = 3.8 Ohm/sq) compared to the ITO/Ag/ITO structure (T_av = 71.6% and R_surf = 3.9 Ohm/sq, respectively). Subsequent testing the stability of the three-layer structures to various heating modes revealed that both structures exhibit tolerance to thermal annealing at T ≤ 250°C both under vacuum and in air. Annealing of the three-layer structures in air at higher temperatures showed that the IGZO/Ag/IGZO structure retains its integrity and functionality up to T = 350°C, whereas integrity of the ITO/Ag/ITO structure is large-scale compromised at this temperature.