Influence Of The Metallic Electrodes On The Contact Resistance Of The In-Ga-Zn Oxide TFTs

Thin Film Transistor is a field effect device, which is composed of electrodes,semiconductor layer and insulating layer. It is the core components of Liquid CrystalDisplay (LCD) and Active Matrix Organic Light Emitting Diode (AMOLED) drivecircuit. The current mainstream LCD screen use poly crystalline silicon TFT oramorphous silicon TFT. However, polysilicon has complex manufacture, high costand poor uniformity. Besides, it’s difficult to produce extensively. Although the carriermobility of the amorphous silicon is not very low, the degree of refinement is still nothigh. So it restricts the development of a new generation of AMOLED displaytechnology. In recent years, the broad band gap oxide semiconductor has made greatprogress, especially the transparent amorphous indium gallium zinc oxide thin filmtransistor (IGZO-TFT). It is better than the amorphous silicon in the carrier mobility,transmittance and uniformity. And it can be produced in a low temperature. What’smore, a higher degree of refinement can be got. This article focuses on differentelectrode materials and the influence of annealing temperature on the deviceperformance.The influence of the metallic electrode materials on the contact resistance of theink-jet printed In-Ga-Zn oxide (IGZO) thin film transistors (TFTs) is investigated inthis paper. Various electrodes, including Al, Ti/Au, ITO and Au were examined basedon the inverted staggered (bottom gate top contact) IGZO TFTs. Without additionalannealing, the contact resistance increased with the increase of the work function ofthe electrode, which is Al <Ti/Au <ITO <Au. However, the contact resistancebehavior changed drastically for different electrodes under different annealingtemperature from200to500oC. The different behavior of the electrodes uponannealing was regarded to the contact modes changed between ohmic and Schottkycontact. The finding provides a clue for electrode selection for the ink-jet printedIGZO TFTs to minimize the contact resistance and optimize the device performanceaccording to the process conditions.