基于In-Ga-Zn-O薄膜的透明阻变及自整流特性研究

发布时间：2018-04-03 06:43

本文选题：透明阻变存储器　切入点：In-Ga-Zn-O　出处：《河北大学》2015年硕士论文

【摘要】：阻变存储器(RRAM)因具有简单结构、低功耗和高速等优点而受到广泛关注。特别是透明阻变存储器(TRRAM)兼备高透明度的优点而引起人们兴趣。具有自整流特性的阻变存储器不仅可以实现高密度存储而且能减小串扰的影响。同时,非晶铟镓锌氧(In-Ga-Zn-O)薄膜因具有迁移率高,工艺温度低以及透明度高等特性而被广泛研究。所以,本论文制备了双极型的α-IGZO/Sr Ti O3/α-IGZO、高透明度的α-IGZO/Ga2O3/α-IGZO以及具有自整流特性的Ag/In-Ga-Zn-O/Pt阻变存储器。并研究了器件的阻变性能和存储机理。主要工作如下:采用磁控溅射和脉冲激光沉积(PLD)技术在石英衬底上制备了α-IGZO/STO/α-IGZO双极型透明阻变存储器。研究了器件的透过率、电流-电压特性(I-V)、保持特性、抗疲劳特性以及导电机制。通过X射线衍射(XRD)观察到薄膜均为非晶态。通过紫外分光光度计观察到器件在可见光范围内的平均透过率为75%。器件的高阻态(HRS)和低阻态(LRS)的电阻比值为6,有效开关可操作250次以上。器件在经过5×104s的测试后,高、低阻态的保持特性依旧保持稳定。对器件的高、低阻态进行拟合,表明导电机制以空间电荷限制电流(SCLC)为主。主要是由于陷阱俘获和释放电子影响了导电电子的变化,进而使电流发生改变。采用磁控溅射技术制备α-IGZO/Ga2O3/α-IGZO结构的透明阻变存储器,中间介质层选用透明性质更优秀的宽带隙半导体材料Ga2O3。透明阻变存储器在可见光范围内的平均光学透过率为91.7%(最大值为98.3%,最小值为81.3%),Ga2O3的光学带隙为5.1e V。研究发现激励电压极性的不同,会影响器件中氧空位的分布,造成阻变特性曲线方向的不同。变温测试透明阻变存储器,拟合为跳跃电导机制。并得到高、低阻态的陷阱跳跃距离分别是1.4nm和0.7nm,高、低阻态的激活能为0.23e V和0.15e V。基于In-Ga-Zn-O薄膜做中间介质层制备的Ag/In-Ga-Zn-O/Pt阻变存储器。研究发现器件在低阻态时,表现出自整流性质。测试温度范围为303K-393K,器件的自整流性质依旧保持稳定。分别采用Cu,Ti和Ag作器件的上电极,自整流性质随电极功函数的变大而越发明显。器件的电极尺寸影响电阻的变化。高阻态符合空间电荷限制电流机制,低阻态符合肖特基发射机制,变温测试得到肖特基势垒高度为0.32e V,动态介电常数εr为7.9。同时,研究认为上电极与In-Ga-Zn-O界面的肖特基势垒是产生自整流特性的主要原因。
[Abstract]:Resistive memory (RRAM) has attracted much attention because of its simple structure, low power consumption and high speed.In particular, transparent resistive memory (TRRAM) has the advantages of high transparency.Resistive memory with self-rectifying characteristics can not only achieve high density storage but also reduce crosstalk.At the same time, amorphous indium gallium zinc oxide In-Ga-Zn-O (In-Ga-Zn-O) thin films have been widely studied because of their high mobility, low temperature and high transparency.Therefore, the bipolar 伪 -IGZO / Sr TIO _ 3 / 伪 -IGZO, the transparent 伪 -IGZO / Ga _ 2O _ 3 / 伪 -IGZO and the self-rectifying Ag/In-Ga-Zn-O/Pt resistive memory have been prepared in this thesis.The resistance performance and storage mechanism of the device are also studied.The main work is as follows: 伪 -IGZO / 伪 -IGZO bipolar transparent resistive memory was fabricated on quartz substrate by magnetron sputtering and pulsed laser deposition (PLD) technique.The transmittance, current-voltage characteristics, retention characteristics, fatigue resistance and conduction mechanism of the devices are studied.The films were observed to be amorphous by X-ray diffraction (XRD).The average transmittance of the device in the visible range is 75 by UV spectrophotometer.The resistance ratio of high resistance HRS and low resistance LRS is 6, and the effective switch can be operated more than 250 times.After testing for 5 脳 10 ~ 4 s, the holding characteristics of high and low resistance state are still stable.By fitting the high and low resistance states of the devices, it is shown that the main conduction mechanism is the space charge-limited current (SCLC).The main reason is that the trapping and releasing of electrons affect the change of conducting electrons, which makes the current change.The transparent resistive memory with 伪 -IGZO / 伪 -IGZO structure was fabricated by magnetron sputtering technique.The average optical transmittance of transparent resistive memory in the visible range is 91.7 (the maximum value is 98.3 and the minimum value is 81.3 / Ga _ 2O _ 3). The optical band gap of the transparent resistive memory is 5.1 EV.It is found that the different polarity of excitation voltage will affect the distribution of oxygen vacancy in the device, resulting in different directions of the resistance curve.Variable temperature test transparent resistive memory, fit to jump conductivity mechanism.The trap jump distances of high and low resistance states are 1.4nm and 0.7 nm, respectively. The activation energies of high and low resistance states are 0.23 EV and 0.15 EV, respectively.Ag/In-Ga-Zn-O/Pt resistive memory based on In-Ga-Zn-O thin film as intermediate dielectric layer.It is found that the device exhibits self-rectifying property in low resistance state.The test temperature range is 303K-393K, and the self-rectifying property of the device remains stable.Using Cu-Ti and Ag as the upper electrodes, the self-rectifying property becomes more and more obvious with the increase of the work function of the electrode.The electrode size of the device affects the resistance.The high resistance state accords with the space charge limiting current mechanism, and the low resistance state accords with the Schottky emission mechanism. The Schottky barrier height is 0.32 EV and the dynamic dielectric constant 蔚 r is 7.9.At the same time, the Schottky barrier between the upper electrode and the In-Ga-Zn-O interface is considered to be the main reason for the self-rectifying characteristics.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TP333;TB383.2

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