基于超薄Al2O3栅绝缘层的低工作电压IGZO薄膜晶体管及其在共源极放大器中的应用

随着薄膜晶体管(Thin-film transistor,TFT)在各类新兴电子产品中得到广泛应用,作为各类电子设备的关键组件,其工作电压和稳定性面临着巨大挑战。为了满足未来高度集成化、功能复杂的应用场合,实现其低工作电压和高稳定性就变得异常重要。我们在150 mm×150 mm大面积玻璃基底上,采用磁控溅射非晶铟镓锌氧化物(amorphous indium-gallium-zinc-oxide,a-IGZO)作为有源层,以原子层沉积(ALD)Al2O3为栅绝缘层,制备了底栅顶接触型a-IGZO TFT,并研究了50,40,30,20 nm超薄Al2O3栅绝缘层对TFT器件的影响。其中,20 nm超薄Al2O3栅绝缘层TFT具有最优综合性能:1 V的低工作电压、接近0 V的阈值电压和仅为65.21 mV/dec的亚阈值摆幅,还具有15.52 cm^2/(V·s)的高载流子迁移率以及5.85×10^7的高开关比。同时,器件还表现出优异的稳定性:栅极±5 V偏压1 h阈值电压波动最小仅为0.09 V以及优良的150 mm×150 mm大面积分布均一性。实现了TFT器件的低工作电压和高稳定性。最后,以该TFT器件为基础设计了共源极放大器,得到14 dB的放大增益。

Low Operating Voltage IGZO Thin-film Transistor Based on Ultrathin Al2O3 Gate Insulator and Its Application in Common-source Amplifier

With the wide application of thin-film transistor(TFT)in various emerging electronic products,as a key component of various electronic equipment,its operating voltage and stability are facing great challenges.In order to meet the needs of highly integrated and complex applications in the future,it is very important to realize its low operating voltage and high stability.Bottom gate top-contact a-IGZO TFT on large area glass substrate of 150 mm×150 mm was prepared by using magnetron sputtering to investigate the effect of 50,40,30 and 20 nm Al2O3 thickness on the performance of a-IGZO TFTs.The results show that TFT with 20 nm-thick-Al2O3 gate insulator exhibits the best electrical comprehensive performance:low operating voltage of 1 V,threshold voltage of nearly 0 V and subthreshold swing of only 65.21 mV/dec.It also has a high field-effect mobility of 15.52 cm^2/(V·s)and a high ION/IOFF ratio of 5.85×10^7.At the same time,the device also shows excellent stability:the minimum threshold voltage shift after 1 h of gate±5 V bias is only 0.09 V and excellent stability of uniform distribution over a large area of 150 mm×150 mm.The low operating voltage and high stability of TFT devices are realized.Finally,a common-source amplifier is designed with this TFT device,and a gain of 14 dB is obtained.