He plasma treatment of transparent conductive ZnO thin films

Selective metallization of amorphous-indium–gallium–zinc-oxide thin-film transistor by using helium plasma treatment

“…This demonstrates that no phase transition occurred during the He plasma treatment and the a-IGZO films retained their amorphous structure. It has been observed in previous reports, as well as in this study, that He plasma treatment induces a change in the chemical bonding configuration of a-IGZO films by breaking of M-O bonds, leading to the formation of oxygen vacancies [12,13]. Through the analyses carried out, it can be seen that the He plasma treatment on a-IGZO films leads to an increase in charge carrier concentration by creating more oxygen vacancies, while retaining the a-IGZO band gap, the amorphous structure of the films and leaving no apparent damages on the surface [12,37].…”

“…One of these issues is the contact resistance at the interface between the a-IGZO channel layer and source/drain (S/D) electrodes, which limits the performance of the TFTs [8][9][10][11]. Various plasma treatments using hydrogen (H 2 ), argon (Ar), helium (He), nitrous oxide (N 2 O), and nitrogen (N 2 ) gases have been extensively investigated to reduce the contact resistance of a-IGZO TFTs by making heavily n-doped a-IGZO contact regions [12][13][14][15]. The contact resistance relies on the carrier concentration of a-IGZO contact region [3], thus these plasma treatments are a simple and effective way to improve the TFT performances as they increase the carrier concentration in the exposed areas [16][17][18][19].…”