铋掺杂对SrTiO3薄膜微观结构及阻变行为的影响

采用溶胶-凝胶及快速退火工艺在p+-Si上制备了Bi掺杂SrTiO_3薄膜,构建了Ag/Sr_(1-x)Bi_xTiO_3/p+-Si结构阻变器件,研究了Bi掺杂量对薄膜微观结构、器件阻变行为及特性的影响。结果表明:Bi掺杂量较低时并未改变Sr_(1-x)Bi_xTiO_3薄膜的相结构,但随着掺杂比例的增大,晶粒尺寸也明显增大,当掺杂量x=0.16时,有Bi4SrTi4O15及TiO2相形成;不同Bi掺杂量的Ag/Sr_(1-x)Bi_xTiO_3/p+-Si器件均呈现出双极性阻变特性,且有明显的多级阻变行为。随Bi掺杂量的增加,器件的阻变性能逐步提高,当x=0.12时器件的高、低阻态电阻比值最大,达到105左右,并且在2 000次可逆循环测试下,高、低阻态电阻比未出现衰减,表现出良好的抗疲劳特性,但当掺杂量x达到或超过0.16后,器件的性能呈下降趋势。Bi掺杂量的增大会导致器件高阻态时的导电机制从空间电荷效应(SCLC)导电机制(x0.16)转变为肖特基势垒发射(x=0.16)。器件在低阻态下均遵循欧姆导电机制。

Effects of Bismuth Doping Concentration on Microstructure and Resistance Switching Behavior of SrTiO3 Films

A series of bismuth-ion-doped SrTiO3 thin films were deposited on p+-Si substrates via a sol-gel process and the subsequent rapid annealing technique,to fabricate the sandwich structures of Ag/Sr1-xBixTiO3/p+-Si for resistance-switching de-vice.The effects of Bi-ion doping concentration on microstructure of the thin film,and resistance switching behavior of Ag/Sr1-x-BixTiO3/p+-Si devices were investigated.The results showed that a low amount of Bi causes no change in the phase structure of Sr1-xBixTiO3 thin films,but an obvious increment of grain size can be observed with the increasing Bi doping content.The Bi4SrTi4O15 and TiO2 phaseswillformwhenthedopingamountisx＝0.16.AlloftheAg/Sr1-xBixTiO3/p+-Sidevicesexhibitbipo-lar resistive and multi-level resistance switching behaviors.The increasing Bi doping concentration also leads to a biphasic (increase→decrease)change in the device’s resistance switching property;when x＝0.12 the device shows the maximum high/low resistance ra-tio of 105 and better reading endurance after 2 000 cycles,but the device performance decays while x＝0.16.This can be explained by the change of dominant conduction mechanism under HRS (high resistance state)induced by Bi doping,from space charge limited current (SCLC)(x＜0.16)to Schottky barrier emission (x＝0.16).All the devices conduct current in accordance with the filamentary theory under LRS (low resistance state).