Pulsed Nd:YAG laser deposition of indium tin oxide thin films in different gases and organic light emitting device applications

The microstructures, electrical and optical properties of indium-doped tin oxide (ITO) films, deposited on glass substrates in different background gases by a pulsed Nd:YAG laser, were characterized. The optimal pressure for obtaining the lowest resistivity in ITO thin film is inversely proportional to the molecular weight of the background gases, namely the argon (Ar), oxygen (O2), nitrogen (N2) and helium (He). While substrate heating to 250 °C decreased the ITO resistivity to < 4 × 10− 4 Ω cm, obtaining the optical transmittance of higher than 90% depended mainly on the background gas pressure for O2 and Ar. Obtaining the lowest ITO resistivity, however, did not beget a high optical transmittance for ITO deposition in N2 and He. Scanning electron microscope pictures show distinct differences in microstructures due to the background gas: nanostructures when using Ar and N2 but polycrystalline for using O2 and He. The ITO surface roughness varied with the deposition distance. The effects on the molecularly doped, single-layer organic light emitting device (OLED) operation and performance were also investigated. Only ITO thin films prepared in O2 and Ar are suitable for the fabrication OLED with performance comparable to that fabricated on the commercially available, magnetron-sputtered ITO.