The Influence of In/Zn Ratio on the Performance and Negative-Bias Instability of Hf–In–Zn–O Thin-Film Transistors Under Illumination

Park

et al. 2013

Jpn. J. Appl. Phys.

In this study, highly reliable amorphous oxide semiconductor-based thin-film transistors (TFTs) were developed. The Hf concentration was systematically changed in the Hf-incorporated In-Zn-O (HIZO) TFTs, and Hf played an important role in determining the negative bias-illumination instability. The process parameters were optimized in order to obtain HIZO TFTs with an excellent stability. HIZO can be processed on a 6-in. wafer at low temperatures and is almost transparent in the visible range. Thus this material is promising for use in current TFTs as well as future transparent electronic device components with good electrical performance and excellent stability.

Section: Resultssupporting

confidence: 50%

Effects of Hf Incorporation on Negative Bias-Illumination Stress Stability in Hf–In–Zn–O Thin-Film Transistors

Park

et al. 2013

Jpn. J. Appl. Phys.

“…An important performance metric, particularly for the TFTs in FPDs, is the operational device stability under illumination2578, i.e., when both light and electrical bias are applied simultaneously. In the dark, IZO TFTs show very stable performance with almost no V T shift (ΔV T ) as a function of stress time (see Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

“…6), which is also critical for the high mobility78, leads to slow decay of photogenerated current when light and negative gate bias are applied, and hence significantly compromises device stability by shifting the threshold voltage91011. This negative-bias illumination (NBI) instability makes AOS remain conductive for several hours/days, even in the absence of light.…”

mentioning

confidence: 99%

Anion control as a strategy to achieve high-mobility and high-stability oxide thin-film transistors

Jeon

Park

et al. 2013

Sci Rep

Self Cite

151

125

Ultra-definition, large-area displays with three-dimensional visual effects represent megatrend in the current/future display industry. On the hardware level, such a “dream” display requires faster pixel switching and higher driving current, which in turn necessitate thin-film transistors (TFTs) with high mobility. Amorphous oxide semiconductors (AOS) such as In-Ga-Zn-O are poised to enable such TFTs, but the trade-off between device performance and stability under illumination critically limits their usability, which is related to the hampered electron-hole recombination caused by the oxygen vacancies. Here we have improved the illumination stability by substituting oxygen with nitrogen in ZnO, which may deactivate oxygen vacancies by raising valence bands above the defect levels. Indeed, the stability under illumination and electrical bias is superior to that of previous AOS-based TFTs. By achieving both mobility and stability, it is highly expected that the present ZnON TFTs will be extensively deployed in next-generation flat-panel displays.

“…In particular, the undercoordinated In atoms are most influential in lowering the conduction band, and this is consistent with the experimental finding that In-rich compounds are more prone to the instability problem. 37,38 Next, we calculate the optical spectrum. The optical absorption coefficient (α) at the photon energy of E ph is given as follows:…”

Section: We Fit Dos Near the Band Edges Using The Form Of D V(c) (E) mentioning

confidence: 99%

Intrinsic nature of visible-light absorption in amorphous semiconducting oxides

Kang¹,

Song²,

Nahm³

et al. 2014

APL Materials

To enlighten microscopic origin of visible-light absorption in transparent amorphous semiconducting oxides, the intrinsic optical property of amorphous InGaZnO4 is investigated by considering dipole transitions within the quasiparticle band structure. In comparison with the crystalline InGaZnO4 with the optical gap of 3.6 eV, the amorphous InGaZnO4 has two distinct features developed in the band structure that contribute to significant visible-light absorption. First, the conduction bands are down-shifted by 0.55 eV mainly due to the undercoordinated In atoms, reducing the optical gap between extended states to 2.8 eV. Second, tail states formed by localized oxygen p orbitals are distributed over ∼0.5 eV near the valence edge, which give rise to substantial subgap absorption. The fundamental understanding on the optical property of amorphous semiconducting oxides based on underlying electronic structure will pave the way for resolving instability issues in recent display devices incorporating the semiconducting oxides.