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利用氩离子束镀膜技术,在N型(100)硅单晶片上淀积钛酸钡膜,并制成MIS结构.在室温下测试其电容-相对湿度(C-RH)特性和电流-相对湿度(I-RH)特性.研究退火条件与固定电荷密度和吸湿灵敏度的关系.结果表明:当相对湿度从12%变化到92%时,在1MHz的测试频率下,电容值变化了48%.在3V偏压下,电流变化了430%,且高湿时的灵敏度比低温时高.随着膜中氧组分的增大,固定电荷密度减小,吸湿响应时间增长,电流变化率下降.文中利用等效方法确定膜中的孔隙体积比和BaTiO,成分的介电常数,建立了描述C-RH特性的物理吸附模型.考虑化学吸附产生的H~+对界面势垒和电场的影响,结合Fowler-Nordheim(F-N)隧穿机构对I-RH特性进行了解释.
Barium titanate films were deposited on N-type (100) silicon wafers and fabricated into MIS structures by Ar ion beam-coating technique.The capacitance-relative humidity (C-RH) and current-relative humidity (I-RH) characteristics.The relationship between annealing conditions and fixed charge density and hygroscopic sensitivity was studied.The results show that when the relative humidity changes from 12% to 92%, the capacitance changes 48% at 1MHz test frequency. With the bias voltage of 3V, the current change is 430%, and the sensitivity of high humidity is higher than that of low temperature.With the increase of the oxygen content in the membrane, the fixed charge density decreases, the hygroscopic response time increases and the current change rate decreases. The equivalent pore-volume ratio, the dielectric constant of BaTiO and the composition of the films were determined by the equivalent method, and a physical adsorption model was established to describe the C-RH characteristics.Considering the influence of H ~ + generated by chemical adsorption on the interface barrier and electric field, The Fowler-Nordheim (FN) tunneling mechanism explains the I-RH characteristics.