Effect of film thickness on the properties of indium tin oxide thin films

Transparent conducting indium tin oxide (ITO) thin films (40-870 nm) were g rown by pulsed laser deposition on amorphous substrates and the structural, electrical, and optical properties of these films were investigated. Films were deposited using a KrF excimer laser (248 nm, 30 ns FWHM) at a fluence of 2 J/cm(2), at substrate temperature of 300 degreesC and 10 mTorr of oxy gen pressure. For ITO films (30-400 nm thickness) deposited at 300 degreesC in 10 mTorr of oxygen, a resistivity of 1.8-2.5x10(-4) Omega cm was observ ed and the average transmission in the visible range (400-700 nm) was about 85%-90%. The Hall mobility and carrier density for ITO films (40-870 nm th ickness) were observed to be in the range of 24-27 cm(2)/V s and 8-13x10(20 ) cm(-3), respectively. The ITO films have been used as the anode contact i n organic light emitting diodes and the effect of ITO film thickness on the device performance has been studied. The optimum thickness of the ITO anod e for the maximum device efficiency was observed to be about 60-100 nm. The device with the optimum thickness of ITO anode showed an external quantum efficiency of about 0.85% at 100 A/m(2). (C) 2000 American Institute of Phy sics. [S0021-8979(00)08622-9].