High-performance amorphous gallium indium zinc oxide thin-film transistors through N2O plasma passivation

Abstract

Amorphous-gallium-indium-zinc-oxide (a-GIZO) thin filmtransistors (TFTs) are fabricated without annealing, using processes and equipment for conventional a-Si:H TFTs. It has been very difficult to obtain sound TFT characteristics, because the a-GIZO active layer becomes conductive after dry etching the Mo source/drain electrode and depositing the a-SiO2 passivation layer. To prevent such damages, N2O plasma is applied to the back surface of the a-GIZO channel layer before a-SiO2 deposition. N2O plasma-treated a-GIZO TFTs exhibit excellent electrical properties: a field effect mobility of 37cm2∕Vs, a threshold voltage of 0.1V, a subthreshold swing of 0.25V/decade, and an Ion∕off ratio of 7.

Effects of ambient atmosphere on the transfer characteristics and gate-bias stress stability of amorphous indium-gallium-zinc oxide thin-film transistors

“…11,13 The role of hydrogen in ZnO-based oxide TFTs has been understood as a donor that increases the conductivity of a-oxide TFTs but little work has investigated its role in the stability of a-oxide TFTs. 16,17 In this work, we investigated the transfer characteristics and gate-bias stability of amorphous indium-gallium-zinc oxide thin film transistors ͑a-IGZO TFTs͒ as a function of different ambient conditions. It was found that hydrogen can play an important role in the instability of a-IGZO TFTs under gate-bias stresses.…”

He plasma treatment of transparent conductive ZnO thin films

“…The incorporated hydrogen also passivates defects at grain boundaries, but the crystalline structures of ZnO were hardly affected. The work function (ϕ) of source/drain electrodes for thin film transistors (TFTs) limits the current conduction of TFTs [5]. There is a trend that for TFTs the contact resistance decreases and current increases with decreasing the ϕ of source/drain electrodes [6].…”

Facilitation of the four-mask process by the double-layered Ti/Si barrier metal for oxide semiconductor TFTs

“…Then N 2 O plasma irradiation was carried out on the IGZO surface (i.e. Si-etched surface) before the formation of passivation layers using SiN/SiO 2 films [11]. Post-annealing was carried out at either 250 • C or 350 • C for 30 min.…”