MOCVD and properties of in situ doped Pt-SnO2 thin films

Intrinsic and in situ Pt-doped SnO2 thin films were deposited in the temper ature range 320-440 degrees C by MOCVD using SnEt4 and Pt(hfa)(2) as metal- organic precursors and O-2 as added oxidant. The growth rate is slightly in hibited by addition of dopant molecules and the process is thermally activa ted. The Pt content of the films increases with Pt(hfa), mole fraction and the growth temperature. Typically, layers containing 0.8 at. % Pt have been prepared at 380 degrees C. Platinum is uniformly distributed through the t hickness of the films. The good efficiency of this in situ doping process i s revealed by the decrease of the room temperature resistivity as the Pt co ntent of the films increases. Pt-SnO2 layers exhibit a thermal stability hi gher than that of undoped films. Preliminary responses as gas sensor have s hown that the detection sensitivity to ethanol in dry air is increased by a factor higher than 2 for Pt-doped SnO2 relative to undoped layers.