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In this work, amorphous praseodymium-doped In-Sn-Zn-O (ITZO-Pr) thin-film transistors (TFTs) were fabricated with improved negative-bias illumination stress (NBIS) stability under different radio frequency (RF) magnetron sputtering powers. The optimized ITZO-Pr TFTs presented field effect mobility ($\boldsymbol {\mu }_{\text{FE}}$) of 20.9 cm $^{2}\cdot {}\text{V}^{-1}\cdot {}\text{s}$ −1, steep subthreshold (SS) of 0.27 V/dec, and small threshold voltage shift (${\Delta } {V}_{\text{th}} = -2.12$ V) under NBIS (−20 V, 3600 s). All Pr-doped devices exhibited a reduction in light responsivity of more than one order of magnitude compared with ITZO TFTs. Moreover, after Pr doping, relaxation processes of photoelectrons changed and then the activation energy (${E}_{\text{a}}$) of light-induced electrons relaxation decreased, which enhanced the NBIS stability of ITZO TFTs effectively. [ABSTRACT FROM AUTHOR]

In this work, we study the intrinsic connection between target quality and performance of sputtered In-Sn-Zn-O (ITZO) thin-film transistors. Using a dense target, the ITZO device overall performance can be improved synergistically. The optimized device exhibits a steep subthreshold swing of 0.13 V/decade, a high on/off current ratio of 2.47 × 108, a threshold voltage of −0.03 V, a saturation field-effect mobility (μFE) of 36.1 cm2/Vs, and a small threshold voltage shift (Δ Vth) of −0.55 V under negative bias stress (−20 V, 3600 s). In contrast, the μFE shows a reverse trend to Δ Vth when using a target with a relatively small density and poor crystallinity. In this case, although the amount of oxygen vacancy in the films can be reduced for better stability via increasing the sputtering power, the film density observably drops due to serious preferential sputtering, leading to smaller μFE. [ABSTRACT FROM AUTHOR]

Thin-film transistors (TFTs) with ScInO or MgScInO semiconductors were fabricated with the annealing temperature of only 150 °C. Compared with ScInO TFT, MgScInO TFT exhibited much better stability under negative-bias temperature stress (NBTS) at 60 °C with negative turn-on voltage (${V}_{ \mathrm{\scriptscriptstyle ON}}$) shift of −0.6 V at the initial stress stage (≤;900 s) and then positive $V_{ \mathrm{\scriptscriptstyle ON}}$ shift (>900 s). First-principles calculations show that the oxygen vacancies (${V}_{\text {O}}$) tend to be bounded with Mg and form Mg– ${V}_{\text {O}}$ pairs with activating (or binding) energy of greater than 0.1369 eV, which is ascribed to the NBTS stability improvement for MgScInO TFT. [ABSTRACT FROM AUTHOR]

It is difficult to implement high-resolution layer-to-layer alignment by direct inkjet printing because of the limitation of position accuracy of the common inkjet printer. The poor alignment of conventional printers generally causes large parasitic overlap capacitances between the gate and source/drain (S/D) of thin-film transistors (TFTs), which degrades device operating speeds. In this paper, a self-aligned method was proposed to minimize the parasitic overlap capacitance. In this method, a hydrophobic fluoropolymers (Cytop) coffee stripe prepared by inkjet printing was utilized to define the gate electrodes, and to dewet deposited ink droplet for self-aligned S/D electrodes. This kind of inkjet-printed self-aligned TFTs with In0.95Sc0.05Ox channel layer have a parasitic overlap capacitance as small as 0.31–0.45 pF. The TFTs in array exhibited an on/off ratio larger than $\textsf {10}^{\textsf {7}}$ and a maximum saturation mobility of $\textsf {4.63}\,\,\textsf {cm}^{\textsf {2}}\,\,\textsf {V}^{-\textsf {1}}\textsf {s}^{-\textsf {1}}$. [ABSTRACT FROM AUTHOR]

Tunable threshold voltage of a thin-film transistor (TFT) is highly desirable for designing multifunctional electronic circuits. In this letter, an ultrathin SnOx capping layer was adopted to modify the threshold voltage of bottom-gate amorphous indium–gallium–zinc-oxide (a-IGZO) TFTs. A threshold voltage shift from 15.2 to −9.0 V was observed as the SnOx thicknesses increased from 0 to 19 nm, accompanying by a sizable increase of the intrinsic electron concentration in the channel layer. It was believed that the SnOx capping layer can extract loosely bound oxygen from the a-IGZO, which was supported by the SnOx composition variation with its thickness. Combining an uncovered a-IGZO TFT with a SnOx capped a-IGZO TFT, an enhancement/depletion inverter with a voltage gain of up to 45.9 was successfully demonstrated. [ABSTRACT FROM AUTHOR]