氧化锌薄膜晶体管的光诱导不稳定性

Photo-Induced Instability of ZnO-Based Thin Film Transistors

为促进氧化锌薄膜晶体管(ZnO-TFT)在有源驱动平板显示领域中的实际应用,以高纯氧化锌(ZnO)为靶材,采用射频磁控溅射法沉积ZnO薄膜作为半导体活性层,制备出ZnO-TFT,研究了可见光诱导引起的器件特性的不稳定性.实验结果表明:在可见光照射下,该ZnO-TFT器件呈现出一定程度的不稳定性;随着光照强度的增加,迁移率稍有增大,阈值电压有微弱的减小;漏电流的相对变化量受栅电压控制,即在开态时相对变化量较小,对于2210 lx的照射强度,相对变化量的最小值为0.58,而在亚阈值区和关态时,漏电流受光照强度的影响较大,在相同强度的光照射下相对变化量的最大值为36.29.对可见光诱导不稳定性恢复过程的研究发现,光照关断后的恢复过程相对缓慢,且随时间呈现出先快后慢的现象.

In order to promote the commercial application of ZnO-based thin film transistors（ZnO-TFTs） to activedriving flat display field,TFTs with ZnO as the channel layer were fabricated via the RF（Radio Frequency） magnetron sputtering with undoped ZnO target.Then,the photo-induced instability of the devices was investigated under visible light illumination.Experimental results indicate that（1） the ZnO-TFT device exhibits light-induced instability under visible light illumination;（2） with the increase of illumination intensity,the carrier mobility of the device slightly increases,while the threshold voltage weakly reduces;and（3） the relative variation of drain current is strongly modulated by gate voltage,for instance,it becomes smaller with a minimum of 0.58 at 2 210 lx when the device operates in the on-state mode,but becomes larger with a maximum of 36.29 at the same illumination intensity when the device operates in the subthreshold or off-state mode.Moreover,it is also found that,the recovery of the photo-induced instability is relatively slow and tends to slow down with the passage of time.