溶胶—凝胶法制备ZnO压敏薄膜及其性能研究

【作者】 刘财坤；

【导师】 邓宏；

【作者基本信息】 电子科技大学 ， 材料物理与化学， 2007， 硕士

【摘要】 ZnO压敏电阻是一种广泛应用于各种电路过电压保护和浪涌吸收的电子元件。随着大规模、超大规模集成电路的飞速发展,以ZnO为代表的低压压敏电阻器在计算机、通讯设备、铁路信号、汽车行业、微型电机以及各种电子器件的低压电路过流保护问题已经引起关注。对具有高非线性I-V特征、压敏电压低于5V的低电压、小功率压敏电阻器的需要正日益增长。由于ZnO压敏薄膜在降低元件的厚度方面比ZnO陶瓷具有较大的优势,因此ZnO薄膜在开发小功率、低压压敏电阻器方面具有极大的优势和潜力。溶胶-凝胶法可以实现材料化学组成的精确可控,可以合成高均匀性多组分凝胶,且工艺过程简单不需要昂贵的设备等优点,非常有利于ZnO压敏薄膜的改性。本文研究了在Si基片上,溶胶-凝胶法工艺条件对薄膜的结晶、取向状况等的影响,并探讨了溶胶-凝胶法制备ZnO薄膜的过程中,工艺条件对其电性能的影响,以此改善工艺条件,优化薄膜的结构。结果表明:退火温度对ZnO薄膜的结构和压敏性能影响最大,600℃为最佳退火温度。本文通过改变Bi2O3、Co2O3和Cr2O3的掺杂浓度进行优化,研究发现:三种掺杂物的掺杂浓度均为0.5%时,获得的ZnO压敏薄膜电性能最佳,其非线性系数为12.63,压敏电压为3.13V,漏电流为25.34μA。分别对以上三种掺杂物进行研究,在掺杂适当的情况的下, Bi2O3在薄膜退火过程中起到了促进晶界的形成的作用, Co2O3具有增加势垒高度、提高非线性系数的作用,而Cr2O3具有降低漏电流及提高非线性系数的作用。更多还原

【Abstract】 ZnO varistors, a kind of semiconductor, have been widely utilized as transient high-voltage protector and surge arrestor. With the development of LSI (Large Scale Integrated circuit) and GSI (Very Large Scale Integrated circuit), ZnO film varistors, the representational low-voltage varistors, which are used in the computer , communication apparatus , railway signal , automobile industry , subminiature electric motor and various electron devices have aroused people paying close attention to. The demand of varistors which have higher nonlinear coefficient、lower nonlinear voltage and leakage current, is increasingly manifold. ZnO thin films have more advantage of reducing the components’thickness than ZnO ceramic, so ZnO thin films have the potential in empoldering lower power and lower nonlinear voltage varistors.Sol-Gel method can realize the material chemical composition precisely controlled, and can compose well-proportioned multicomponent gel, the technology does not require the expensive instrument, and be propitious to change ZnO thin films’capabilities.In this thesis, ZnO thin films were prepared by sol-gel method on the silicon substrates, and the influence of the process conditions on the crystallization and orientation of the films were studied for improving the process condition and optimizing the microstructure of ZnO thin films. The result indicates that the annealed temperature affects the microstructure and voltage-sensitive capacities of ZnO films mostly, 600℃is the best annealed temperature.In this thesis, we changed the adulteration concentration of Bi2O3、Co2O3 and Cr2O3 to carry out an optimization. The results indicate that when the three kinds additives adulteration concentration are all 0.5%, ZnO thin film varistors have the best voltage-sensitive capacities. The nonlinear voltage of the ZnO thin film varistors was 3.13V, nonlinear coefficient was 12.63, and leakage current was 25.34μA.Under the condition of appropriate adulterations, Bi2O3 can promote the formation of crystal boundaries when the films are annealed, Co2O3 can increase barrier potential altitude and improve the nonlinear coefficient, Cr2O3 can reduce the leakage current and improve the nonlinear coefficient.更多还原