Influence of Si concentration on electrical and optical properties of room temperature ZnO:Si thin films
Résumé
Si-doped Zinc Oxide (SxZO, x from 0 to 4.5 at.%) thin films are grown at room temperature under an oxygen pressure of 1.0 Pa, using Pulsed Laser Deposition. Hall effect measurements report a decrease in resistivity as Si concentration increases from x = 0 to x ~ 1.5% (ρS1.5ZO = 9 × 10− 4 Ω cm) followed by an increase in resistivity as the Si content further increases. The enhancement in resistivity as x increases above ~ 1.5% is associated with a decrease in carrier mobility with no further increase in carrier concentration; it suggests that the additional Si atoms are not only electrically inactive but also act as electron trapping centers suggesting that they are not well incorporated in the ZnO structure. Such observation well agrees with the decrease in crystallinity observed with Si content leading to amorphous films for x as low as 1%, when deposited on glass substrate. Finally, a resistivity as low as 3.3 × 10− 4 Ω cm is reported for S1.5ZO thin films deposited at 100 °C.