摘要
在Ｎ－Ｓｉ〈１００〉衬底制作了１０ｎｍ超薄ＳｉＯ２作介质膜的ＭＯＳ结构．研究了温度从１００～４５０Ｋ电子从Ｓｉ界面积累层Ｆ－Ｎ隧穿超薄ＳｉＯ２的Ｉ－Ｖ特性及低场传输电流随温度的变化关系．研究结果表明：在较低的温度下，电流与温度基本无关；而在较高的温度下，电流随温度指数增加．为从理论上解释这些实验结果，认为在Ｆ－Ｎ隧穿电场范围，电流密度Ｊ１∝Ｆ２ｅｘｐ（－β／Ｆ），而在低场范围电流Ｊ＝Ｊ０＋Ｊ２，Ｊ２∝Ｆｅｘｐ（－Φ２／ｋＴ）．Ｊ０为低场漏电流．Ｊ１从实验数据可以求出，电子从Ｎ型Ｓｉ〈１００〉隧穿超薄ＳｉＯ２的势垒高度为３．１３ｅＶ．在较高温度下，因有效隧穿势垒随温度增加而线性地减少，使隧穿电流指数地增加，证实了Ｎ型Ｓｉ半导体费米能级随温度增加而下移的情形．Ｊ２是较高温度及低场下介质膜中热激活电子从一种孤立态到另一种孤立态的跳跃产生一种欧姆导电特性，并求得了电子热激活能Φ２约为０．１６３ｅＶ．
Abstract The MOS structures of 10nm ultrathin SiO 2 dielectric films have been prepared on the N Si〈100〉substrate. The I V characteristics for electrons tunneling ultrathin SiO 2 films from the Si〈100〉interface accumulation layer and the current transport at lower electric field have been studied at temperatures ranging from 100K to 450K. The experimental results show that at lower temperatures the current bears no relation to temperature and the current increases with temperature at higher temperatures. As a theoretical exposition of the results, it is proposed that in higher field region the F N tunneling current density J 1∝ F 2exp(- β / F )but in lower filed region the total current J=J 0+J 2, here J 0 is the low field leakage current and the transport current J 2 ∝ Fexp (- Φ 2/kT ). From experimental data we estimate that the barrier height of electrons tunneling ultathin SiO films is 3.13eV for N Si〈100〉. At higher temperatures the effective tunneling barrier height decreases linearly when the temperature increases, as a result the tunneling current exponentially increases. The thermal activation energy is about 0.163eV. The hopping of themally excited electrons from one isolated state to another state forms Ohmic characteristics in the dielectric films at higher temperatures and in lower fields.
基金
广东省自然科学基金
香港裘槎基金会资助
