Enhanced Drain Current Ripple Variation with Vertical and Horizontal Electrical Fields under Optical Illumination

摘要

For logic MOSFET (metal-oxide-semiconductor filed effect transistor), the drain current usually depends on applied drain and gate voltages. A continuous-wave (CW) laser-crystallized (CLC) single-grainlike polycrystalline silicon (polysilicon) thin-film transistor (poly-Si TFT) also represents the similar electric characteristics with the mentioned device. Recently, poly-Si n-TFTs had been researched and successfully fabricated by C. Chen's team [1]. This TFT device demonstrates the excellent electron mobility, up to 530 cm~2/V-s greater than that with low-temperature poly-silicon (LTPS) fabrication technology. In general, the TFT device is directly exposed by light from backside light source and outside light source beyond the display screen. Using some illuminants shining on the CLC poly-Si TFT, such as light emitting diode (LED), the current-voltage (I-V) characteristic of the TFT shows a current-ripple phenomenon. These interesting ripples actually may be magnified by the supplied drain and gate voltages. In this work, the red color LED was employed and the supplied drain and gate voltages were 0~ 7 V and 1 ~ 5 V, respectively.