Temperature programmed desorption of F-doped SnO2 films deposited by inverted pyrosol technique

Abstract

Fluorine-doped tin dioxide (FTO) films were deposited on silicon wafers by inverted pyrosol technique using solutions with different doping concentration (F/Sn=0.00, 0.12, 0.75 and 2.50). The physical and electrical properties of the deposited films were analyzed by SEM, XRF, resistivity measurement by four-point-probe method and Hall coefficient measurement by van der Pauw method. The electrical properties showed that the FTO film deposited using the solution with F/Sn=0.75 gave a lowest resistivity of 3.2·10–4 ohm cm. The FTO films were analyzed by temperature programmed desorption (TPD). Evolved gases from the heated specimens were detected using a quadruple mass analyzer for mass fragments m/z, 1(H+), 2(H2+), 12(C+), 14(N+), 15(CH3+), 16(O+), 17(OH+ or NH3+), 18(H2O+ or NH4+), 19(F+), 20(HF+), 28(CO+ or N2+), 32(O2+), 37(NH4F+), 44(CO2+), 120(Sn+), 136(SnO+) and 152(SnO2+). The majority of evolved gases from all FTO films were water vapor, carbon monoxide and carbon dioxide. Fluorine (m/z 19) was detected only in doped films and its intensity was very strong for highly-doped films at temperature above 400°C.