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We studied the optical and electrical properties of the amorphous indium gallium zinc oxide thin‐film transistors (a‐IGZO TFTs). To develop a‐IGZO density‐of‐states model, intrinsic a‐IGZO optical properties such as optical band gap and Urbach energy, and TFT characteristics under illumination are investigated. During the a‐IGZO TFTs illumination with the wavelengths ranging from 460 to 660 nm, the off‐state drain current only slightly increases while a large increase was observed for the wavelength below 400 nm. Threshold voltage and subthreshold swing are also only slightly modified between 460 to 660 nm, while field‐effect mobility is almost unchanged in the investigated photon energy range. The observed results are consistent with the a‐IGZO optical energy band gap of about 3.05 eV. This study suggest that the a‐IGZO TFTs are light sensitive above 3.0 eV and photogenerated electrons are more mobile than holes within device channel region.

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This paper reports on low 1∕f noise, low corner-frequency, piezoresistive microcantilevers suitable for static and slowly time varying, force and displacement sensing applications such as chemical and biosensing. We demonstrate a full bridge, piezoresistive cantilever with greater than 140dB dynamic range, a noise amplitude spectral density floor of 3.7nV∕V√Hz at 0.1Hz. At 1.0Hz, the noise spectral density is 1.2nV∕V√Hz equivalent to 10pN∕√Hz or 5pm∕√Hz. The force resolution over the frequency band of 0.1–100Hz is 100pN.

The paper presents the study of electrical instability of RF sputter amorphous In‐Ga‐Zn‐O (a‐IGZO) thin‐film transistor (TFT) induced by negative steady‐state (or D.C.) bias‐temperature‐stress (BTS). Similarly to positive BTS results [8], the stress time evolution of the threshold voltage shift (Δ Vth) induced by negative BTS under different stress voltages and temperatures can all be described by the stretched‐exponential model. for the first time, we also present the results for Δ Vth under pulse (or A.C.) BTS. The Δ Vth for positive A.C. BTS is found to have a pulse‐period dependence while a huge reduction of Δ Vth is found for all negative A. C. BTS results. This might suggest the time for holes to accumulate near the a‐IGZO/ SiO2 interface is much longer than the time for electrons. The effect of bi‐polar stressing is also discussed.