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We proposed a physical model for ink-jet printed polymeric thin-film transistors (PTFTs) all over the sub- and above-threshold regions by using an effective carrier density. The nonlinearity under the low lateral electric field in the printed thiophene PTFTs was reproduced by applying the back-to-back Schottky diode model based on simple Poole–Frenkel (PF) mobility formalism. The analytical ${I}{-}\!{V}$ model supplemented with ${C}{-}\!{V}$ model in a single framework was also verified by successfully reproducing the measured characteristics of TFTs with three different thiophene polymeric channel materials. Additionally, we applied the physics-based analytical model on the inkjet-printed PTFT-based inverter and confirmed that the proposed models could predict the inverter circuit characteristics of the gain and static noise margin (SNM) based on the physical parameters.

Degradation on the current saturation of the output characteristics in amorphous indium–gallium–zinc–oxide (a-IGZO) thin-film transistors with the bottom-gate structure is investigated. As the drain-to-source voltage ( ${V}_{\textsf {DS}}$ ) increases at a fixed gate-to-source voltage ( ${V}_{\textsf {GS}}$ ), the current from drain to source ( ${I}_{\textsf {DS}}$ ) becomes nonsaturated and increases due to the mobility enhancement and ${I}_{\textsf {DS}}$ also decreases again due to the electron trapping into the gate insulator and/or an interface, which occurs mainly at the channel edge near a drain. Analysis is validated by using the pulsed ${I}_{\textsf {DS}}$ – ${V}_{\textsf {DS}}$ measurement. Nonsaturated current is attributed to the Joule heating-assisted mobility enhancement and the thermally activated electron trapping, which is the reason why the nonsaturation becomes more prominent as the IGZO active thin film becomes thinner. Furthermore, it is found that the rate of the increased ${I}_{\textsf {DS}}$ per increasing ${V}_{\textsf {DS}}$ gets higher as either the channel width ( ${W}$ ) increases or the channel length ( ${L}$ ) decreases; whereas, the rate of the decreased ${I}_{\textsf {DS}}$ per increasing ${V}_{\textsf {DS}}$ becomes higher as the device size, i.e., ${W}\times {L}$ , increases. The former is well correlated with Joule heating while the latter with the self-heating-assisted electron trapping due to a total heat accumulated in an active layer.

We propose a systematic calculation method for negative bias illumination stress (NBIS)-induced instabilities in amorphous InGaZnO thin-film transistors (TFTs). The proposed method is based on activation energy window (AEW) in subgap energy range, and it can reproduce the NBIS time evolution of ${I}$ – ${V}$ characteristics without long-term stress test. Furthermore, it quantitatively explains the effect of oxygen content on the NBIS instability. The AEW, which is employed for emulating the oxygen vacancy ionization, peroxide formation, and hole trapping, has the order of magnitude of 1016–1017 cm−3 for the bias stress of −20 V and the commercial LED backlight of 300 cd/m2. The proposed method is expected to play such an important role in the instability awareness of amorphous oxide TFTs.

We report a technique for separate extraction of extrinsic source/drain (S/D) resistances ( $R_{\mathrm {Se}}/R_{\mathrm {De}})$ and gate bias ( $V_{{\mathbf {GS}}})$ -dependent but channel length (L)-independent intrinsic source/drain ( $R_{\mathrm {Si}}/R_{\mathrm {Di}})$ resistances for the overlap region in MOSFETs. For extraction of the overlap length ( $L_{\mathrm {ov}})$ in the heavily doped S/D regions, an analytical capacitance model for the depletion region is employed with the gate-to-source and gate-to-drain capacitance–voltage ( $C_{{{G-S}}}$ , $C_{{{G-D}}})$ characteristics. After verifying the extracted overlap length through a 2-D technology computer-aided design simulation, we successfully extract $\mathrm{V}_{\mathrm {\mathbf {GS}}}$ -dependent $R_{\mathrm {\mathbf {Si}}}= 0.9{\sim }3.7~\Omega $ and $R_{\mathrm {\mathbf {Di}}}= 1.0{\sim }3.9~\Omega $ in an n-channel MOSFET with $W=140~\mu $ m and $L=0.35 ~\mu $ m. In addition, $V_{\mathrm {\mathbf {GS}}}$ - and $L$ -independent extrinsic S/D resistances are separately extracted to be $R_{\mathrm {Se}}=5.1~\Omega $ and $R_{\mathrm {De}}= 5.0~\Omega $ , respectively.