Transparent conductive Ga-doped MgZnO/Ag/Ga-doped MgZnO sandwich structure with improved conductivity and transmittance

This study presents the advantages of combining Ga-doped MgZnO (GMZO) transparent conductive oxide (TCO) with a silver (Ag) layer to form a GMZO/Ag/GMZO composite structure using a radio-frequency magnetron sputtering and electron beam system. The proposed structure improves the electrical properties of a single GMZO bulk and allows a low processing temperature. This study also investigates the effects of the silver thickness and post-annealing process on the structural, electrical, and optical properties of the GMZO/Ag/GMZO composite sandwich structure. The optimal GMZO/Ag/GMZO structural thickness was 40/20/60 nm, which yielded a resistivity of 5.8 × 10−5 Ω cm with an average transmittance of 81.0% at a wavelength range of 400–800 nm. The figure of merit (ΦTC) for the as-deposited sandwich structure was calculated as 2.1 × 10−2 Ω−1. This is approximately two times higher than the best results obtained from a single GMZO bulk layer with an annealing temperature of 600 °C (1.1 × 10−2 Ω−1). This remarkable improvement of the GMZO/Ag/GMZO sandwich structure is a highly promising candidate for optoelectronic devices, and has a low processing temperature than a single TCO bulk layer.

► Remarkable improvement of the GMZO/Ag/GMZO sandwich structure with resistivity of 10−5 Ω cm without thermal annealing. ► The optimal structural design shows an average transmittance of 81% at a wavelength range of 400–800 nm. ► The AFM were used to verify the morphological study for crystallite size. ► The SEM pictures show the aggregation of the Ag grain leading to the increase of light scattering. ► XPS measurements were employed to confirm the composition and the diffusion of Ag.