Zheng Xue-ren

A two-dimensional flow sensor using integrated silicon spreading-resistance temperature detectors

A simple silicon two-dimensional (2D) flow sensor for the measurement of both flow direction and speed is described. By integrating two couples of silicon spreading-resistance temperature (SRT) sensors in two perpendicular directions on the surface of a silicon chip, this sensor can detect flow speed and flow direction φ in a full range of 360°. Experimental results confirm theoretical analysis that the output of the sensor increases with the square root of the flow velocity, and the outputs in the two perpendicular directions are proportional to sin φ and cos φ, respectively. The effects of sensor layout are also discussed. With complete oxide isolation for the SRT sensors, the flow sensor could achieve higher sensitivity by operating above the intrinsic temperature of silicon (∼150 °C), or could be used to detect fluid flow at a temperature as high as 300 °C.

Modeling of self-heating effects in polycrystalline silicon thin film transistors

An analytical DC model accounting for the self-heating effect of polycrystalline silicon thin-film transistors (poly-Si TFTs) is presented. In deriving the model for the self-heating effect, the temperature dependence of the effective mobility is studied in detail. Based on the mobility model and a first order approximation, a closed-form analytical drain current model considering the self-heating effect is derived. Compared with the available experimental data, the proposed model, which includes the self-heating and kink effects, provides an accurate description of the output characteristics over the linear, the saturation, and the kink regimes.

Analytical drain current model for amorphous IGZO thin-film transistors in above-threshold regime

An analytical drain current model is presented for amorphous In-Ga-Zn-oxide thin-film transistors in the above-threshold regime, assuming an exponential trap states density within the bandgap. Using a charge sheet approximation, the trapped and free charge expressions are calculated, then the surface potential based drain current expression is developed. Moreover, threshold voltage based drain current expressions are presented using the Taylor expansion to the surface potential based drain current expression. The calculated results of the surface potential based and threshold voltage based drain current expressions are compared with experimental data and good agreements are achieved.