Forming high transmittance GaSnO/Ag/GaSnO conducting electrodes for optoelectronic devices

Abstract

We report on the development of high-performance transparent conducing GaSnO (GTO)/Ag/GTO multilayer electrodes for display applications. The optical and electrical characteristics of the GTO/Ag/GTO multilayers were investigated as functions of GTO layer (d(GTO)) and Ag layer (d(Ag)) thicknesses. With increasing d(GTO) from 10 to 50 nm, the sheet resistance slightly increased from 3.83 to 4.81 Omega/sq, the carrier concentration decreased from 4.76 x 10(22) to 1.12 x 10(22) cm(-3), and the mobility (mu) slightly changed from 10.7 to 10.3 cm(2)/V. The 40 nm-thick GTO-based multilayer exhibited the mean transmittance (T-av) of 91.6% and had the Haacke's figure of merit (FOM) of 87.84 x 10(-3) Omega(-1). The mu value increased from 7.97 to 11.67 cm(2)/V and sheet resistance varied from 7.81 to 3.47 Omega/sq as increasing d(Ag) from 9 to 15 nm. The T-av of the GTO (40 nm)/Ag/GTO (40 nm) samples decreased from 94.5% to 84.9% with increasing d(Ag). The optical bandgaps of the GTO and GTO/Ag/GTO (40 nm/12 nm/40 nm) films were estimated to be 4.06 and 3.94 eV, respectively. Finite-difference time-domain calculations were conducted to explain the d(Ag) and d(GTO) dependent transmittance of the GTO/Ag/GTO samples. With the phasor analyses, the d(GTO) dependence of the transmittance of GTO/Ag (12 nm)/GTO multilayers is described and discussed. Furthermore, the optical and electrical features of the optimal GTO/Ag/GTO (40 nm/12 nm/40 nm) electrode are compared with those of sputter-deposited 92 nm-thick indium fin oxide (ITO) films.