The influence of SiOx and SiNx passivation on the negative bias stability of Hf–In–Zn–O thin film transistors under illumination

Abstract

The stability of hafnium indium zinc oxide thin film transistors under negative bias stress with simultaneous exposure to white light was evaluated. Two different inverted staggered bottom gate devices, each with a silicon oxide and a silicon nitride passivation, were compared. The latter exhibits higher field effect mobility but inferior subthreshold swing, and undergoes more severe shifts in threshold voltage (VT) during negative bias illumination stress. The time evolution of VT fits the stretched exponential equation, which implies that hydrogen incorporation during the nitride growth has generated bulk defects within the semiconductor and/or at the semiconductor/gate dielectric interface.

Ultrawide band gap amorphous oxide semiconductor, Ga–Zn–O

“…To date, a variety of crystalline transparent conductive oxides (TCOs) have been reported; however, most of them contain the representative TCOs of ZnO, In 2 O 3 , SnO 2 , and Ga 2 O 3 as major constituents. Development of AOSs has followed a similar manner, leading to a-In-Zn-O, a-Zn-Sn-O, a-In-Ga-O, a-In-Sn-Zn-O, a-Sn-Ga-Zn-O, a-Hf-In-Zn-O, a-Ga-Cd-O [1,[8][9][10][11], etc. Among the crystalline TCOs, pure β-Ga 2 O 3 has the largest E g of 4.9 eV [12]; however, electron conduction in pure amorphous Ga 2 O 3 (a-Ga 2 O 3 ) has not yet been reported.…”

Modeling the behavior of amorphous oxide thin film transistors before and after bias stress

“…Among AOS materials, amorphous In-Ga-Zn-O (a-GIZO) [1][2][3] and more recently Hf-In-Zn-O (HIZO) TFTs [4], which present some advantages with respect to GIZO TFTs, are been systematically studied. However, problems related to the stability with bias, temperature and illumination in these transistors, need to be understood and optimized, [5][6][7][8][9]. As can be seen from previous publications, devices can behave quite differently in dependence on fabrication processes and annealing, as well as on measurement conditions.…”

Characteristics of short-channel amorphous In-Ga-Zn-O thin film transistors and their circuit performance as a load inverter

“…However, the characteristics of TFTs using a short channel regime have rarely been studied. Most previously reported oxide TFTs, although applied in industry, have large physical dimensions (channel lengths > 10 μm) [3,4]. Furthermore, the majority of the work concerned improvements to the characteristics of the TFTs, such as their structure, channel layer, and reliability, rather than their circuit performance [5,6].…”