非晶氧化铝超薄膜中的电荷输运特性

Charge transport in amorphous alumina ultra-thin films

研究了反应射频磁控溅射制备的非晶氧化铝薄膜中电荷输运过程，发现交流和直流电导导电机制是明显不同的．对直流输运，以 Ｐｏｏｌｅ—Ｆｒｅｎｋｅｌ发射模式为主，而新样品的立流电导则常常是带陷阱的空间电荷限制电流模式。交流电导则是由所谓的声子辅助的定域载流子的跳跃引起的。电导的温度特性表明，交流电导有两种不同的导电机制，即低温区的浅陷阱发射和高温区的因氧缺陷导致的深陷阱的发射过程，直流电导与交流电导在高温区趋于一致。

Investigations on the charge transport in amorphous alumina films fabricated by reactive sputtering were carried out at room temperature and in the range from 20 to 300℃. It was found that the conduction mechanisms for DC and for AC were different. For DC case, Poole-Frenkel emission was found to be dominant in transport even in low field. If the sample is newly fabricated, space-charge-limited current (SCLC) can often be observed. For AC case, the transport is determined to be the hopping of the localized e-lectrons near Fermi level. The temperature dependence of both DC and AC conductance showed active-typed conducting feature. AC conductance has two levels of active energy, namely, about 0. 05eV in low-temperature (20℃<T<100℃) region and 0. 4~0. 5eV in high-temperature (100℃<T<300℃) which is also the active energy of DC conductance in the whole temperature range from 20 to 300℃. The dangling bonds of the excessive ocygen in the alumina film were owed to the deeper traps (0. 4~0. 5eV in depth) found in the experiments.