Rapid and selective green laser activation of InGaZnO thin-film transistors through metal absorption

Abstract

We used a pulsed green laser to activate indium gallium zinc oxide thin-film transistors (IGZO TFTs). The IGZO films with large bandgaps (>3 eV) were easily activated by heat delivered by a pulsed green laser to the gate, source, and drain metal electrodes. The IGZO TFTs were quickly and selectively activated in the absence of conventional annealing. Compared to the IGZO TFTs that were annealed at 300°C, the IGZO TFTs that were activated via pulsed green laser irradiation exhibited superior electrical characteristics: a field effect mobility of 11.98 ± 0.64 cm2 V−1 s−1, a subthreshold swing of 0.33 ± 0.02 V dec−1, and an on/off ratio of 8.28 × 109 ± 7.42 × 109, which were attributable to increases in the number of metal–oxide (M-O) bonds and oxygen vacancies, and reduced levels of OH-related species. The pulsed green laser broke weak chemical M-O bonds in the IGZO films through dihydroxylation of the OH-related species, and then strengthened the residual M-O bonds via heat transfer from the metal electrodes. This new activation process could replace conventional annealing and is expected to expand the applications of flexible and transparent devices.