Modulation of electrical and optical properties of doping controlled SnO2 thin-film double layers

SnO 2 -based double-layered thin-film structures were fabricated to enhance two conflicting properties of the electromagnetic interference (EMI) shielding effectiveness and the optical transmittance in the visible and infrared (IR) wavelength ranges. Samarium-doped (SmTO) and fluorine-doped SnO 2 (FTO) thin films were formed by ultrasonic-assisted spray pyrolytic deposition for the high and low electrical resistance layers, respectively. The SmTO and FTO single layers showed difficulties in enhancing the EM shielding efficiency and IR transmittance simultaneously. To modulate the optical and electrical properties individually, a high and low-resistance SmTO/FTO double-layered thin-film structure was designed and deposited. By controlling the thickness of inserted FTO thin film in the double layer, the sheet resistance could be modulated between 167.4 and 393.3Ω/sq. The SmTO/FTO double-layered structure showed an enhanced EMI shielding effectiveness while maintaining the IR transmittance of over 50%. In this way, the electrical properties could be modulated by adopting the double-layered structure of the high and low electrical resistance materials, which resulted in the enhancements of the IR transmittance and EMI shielding performances simultaneously.