Effect of Sn doping on the electronic transport mechanism of indium-tin-oxide films grown by pulsed laser deposition coupled with substrate irradiation

Low-resistivity indium-tin-oxide (ITO) films (8.9 x 10(-5)-2.3 x 10(-4) Omega cm), 80 +/- 20 nm thick grown by combining pulsed laser deposition and laser irradiation of the substrate were studied in relation to tin (Sn) doping content. Films with Sn doping content over the range 0-10 wt % were deposited at room temperature (RT) and 200 degrees C at a fixed oxygen pressure of 1 x 10(-2) Torr. The laser beam with energy density of 70 mJ/cm(2) was directed at the middle portion of the substrate during growth. At RT, the laser-irradiated and nonirradiated parts of the films exhibited crystalline and amorphous phase, respectively. The amorphous films indicated a steady resistivity, carrier concentration, and Hall mobility of similar to 2.4 x 10(-4) Omega cm, 8 x 10(20) cm(-3), and similar to 32 cm(2)/V s, respectively, and showed no significant change over 0-10 wt % Sn doping content. The crystalline films deposited at RT by laser irradiation and 200 degrees C indicated a strong dependence of the resistivity, carrier concentration, and Hall mobility on Sn doping content over the range 0-10 wt %. The Hall mobility of the ITO films steadily decreased with increasing Sn doping content. Study on the scattering mechanisms based on the experimental data and theoretical models showed that the scattering of free carriers in the films was caused mainly by ionized centers. (C) 2000 American Institute of Physics. [S0021-8979(00)01120-8].