TUNNELING RECOMBINATION OF TRAPPED ELECTRONS AND HOLES IN KCL-AGCL AND KCL-TLCL
TUNNELING RECOMBINATION OF TRAPPED ELECTRONS AND HOLES IN KCL-AGCL AND KCL-TLCL
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DOI：
10.1103/physrevb.9.4497
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发表时间：
1974-01-01
影响因子：
3.7
通讯作者：
YUSTER, PH
中科院分区：
文献类型：
--
作者：
DELBECQ, CJ;TOYOZAWA, Y;YUSTER, PH
已经证实，在77K的电离辐射下，KClAgCl2(或KClTlCl2)晶体的空穴陷阱为Cl2−，VK中心为VK，电子为Ag0(Tl0)。这些晶体在77K时发出发光，并在照射后持续数小时。有证据表明，这种余辉是附近金属-原子-Cl2−对之间电子-空穴复合的结果，这种复合不是通过热激活过程而是通过隧道过程发生的。在一个简单模型的基础上，定性地理解了余辉强度的时间依赖性。当Cl2−在晶体中优先取向时，观察到余辉被部分极化，其主要成分的电矢量平行于Cl2−分子轴。如果含有取向Cl2−的晶体被加热，其偏振度保持不变，直到Cl2−以可察觉的速度迷失方向的温度范围内；在后一温度范围内，偏振度变为零，然后反转符号，最后又变为零。当Cl2−改变取向时，这种极化反转被解释为指示隧道几率是各向异性的。
It is well established that exposure of KCl: AgCl (or KCl: TlCl) crystals at 77 K to ionizing radiation results in the trapping of holes as Cl 2−, V K centers, and electrons as Ag 0 (Tl 0). These crystals emit luminescence at 77 K which persists for many hours after the irradiation. Evidence is presented that indicates that this afterglow results from electron-hole recombination between nearby metal-atom-Cl 2− pairs, and that the recombination does not occur by a thermally activated process but by a tunneling process. The time dependence of the intensity of the afterglow is qualitatively understood on the basis of a simple model. When the Cl 2− are preferentially oriented in the crystal it is observed that the afterglow is partially polarized with the electric vector of the dominant component parallel to the Cl 2− molecular axis. If a crystal containing oriented Cl 2− is warmed, the degree of polarization remains constant up to the temperature range where the Cl 2− disorient at an appreciable rate; in the latter range the degree of polarization goes to zero and then reverses sign before finally going to zero again. This reversal of the polarization which occurs when the Cl 2− change orientation is interpreted as indicating that the tunneling probability is anisotropic.