Characteristic of Bismuth-Doped Tin Oxide Thin-Film Transistors

The influences of bismuth doping contents on the structure, morphology and electrical properties of amorphous bismuth-doped tin oxide (a-TBO) thin films have been investigated. With the increase of Bi content, the resistivity of TBO films monotonously increases due to the decreased oxygen vacancies. The thin-film transistors (TFTs) with a-TBO films as channel layers have been prepared on SiO2-Si substrate. Through the comparison of the transfer characteristic curves of the TFTs with different Bi contents, it is observed that Bi doping is useful to suppress the excess carrier concentration and improve the performances. TBO-TFTs with Bi content 2.7 at.% show the optimum performances, with a field effect mobility of 4.7 cm(2)V(-1)s(-1), a threshold voltage of -3.9 V, a subthreshold swing value of 1.3 V/decade, and an ON-OFF current ratio of 2.3 x 10(6). In addition, the bias stress stabilities of intrinsic SnO2 TFTs and a-TBO TFTs were compared and analyzed.