基于蛋清栅介质的超低压双电层薄膜晶体管

Ultralow-voltage albumen-gated electric-double-layer thin film transistors

新一代环保、生物兼容性电子功能器件受到了广泛关注.本文采用具有高质子导电特性的天然鸡蛋清作为耦合电解质膜制备双电层薄膜晶体管,该薄膜晶体管以氧化铟锡导电玻璃为衬底和底电极,以旋涂法制备的鸡蛋清为栅介质,以磁控溅射沉积的氧化铟锌为沟道和源漏电极.实验结果表明,这种基于鸡蛋清的栅介质具有良好的绝缘性,并能在其与沟道界面处形成巨大的双电层电容,从而使得该类晶体管具有超低工作电压(1.5 V)、低亚阈值(164 mV/dec)、大电流开关比(2.4×10~6)和较高的饱和区场效应迁移率(38.01 cm^2/(V·s)).这种以天然鸡蛋清为栅介质的超低压双电层TFTs有望应用于新型生物电子器件及低能耗便携式电子产品.

In recent years, environment-friendly and biocompatible electronics have received extensive attention. As a kind of natural biological material with rich sources, proteins have been widely used in electronic devices. In this work, electricdouble-layer(EDL) thin-film transistors(TFTs) gated by natural chicken albumen are fabricated at room temperature.The indium-tin-oxide(ITO) conductive glass is employed as a substrate. The spin coated chicken albumen film is used as the gate dielectric. The indium-zinc-oxide(IZO) is sputtered on an albumen-coated ITO glass as the channel and the source/drain electrodes with only one shadow mask. The capacitance-frequency measurements demonstrate an ultra-large specific capacitance of the albumen film at low frequencies. For the physical understanding of the capacitive coupling within the albumen film, the phase angle is characterized as a function of frequency. The results indicate that such an ultra-large capacitive coupling can be attributed to the proton migration under the electric field, which results in the EDL effect at the interface of the albumen film. By DC sweep measurements, a low leakage current is observed(< 3.0 nA at Vgs = 1.5 V), which indicates a good isolation of the albumen-based dielectric. By transfer and output measurements, an ultralow operation voltage of 1.5 V, a high field-effect mobility of 38.01 cm2/(V·s), a low subthreshold swing of 164 m V/decade, and a large on-off ratio of 2.4×106 are obtained for such albumen-gated TFTs. The ultra-large EDL capacitive coupling is responsible for such good electrical characteristics. The dynamic bias stress stability of the albumen-gated TFTs is also investigated. The device exhibits a good reproducibility in response to the repeatedly pulsed gate voltage. A maintainable on-to-off ratio(> 106) and no obvious current loss are observed, which suggests that neither chemical doping nor chemical reaction occurs at the albumen-based dielectric/IZO channel interface when the gate potential is biased. After being aged one day in air ambient without surface passivation, the albumen-gated TFTs show a good stability of the electrical properties. Such ultralow-voltage EDL-TFTs gated by albumen electrolyte will be useful for the bioelectronic and low-energy portable electronic products. And our results will also have potential applications in biocompatible artificial neuron networks and brain-inspired neuromorphic systems.