Electrical transport mechanism of the amorphous phase in Cr2Ge2Te6 phase change material
Electrical transport mechanism of the amorphous phase in Cr2Ge2Te6 phase change material
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DOI：
10.1088/1361-6463/aafa94
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发表时间：
2019-03-06
影响因子：
3.4
通讯作者：
Kobayashi, Keisuke
中科院分区：
文献类型：
--
作者：
Hatayama, Shogo;Sutou, Yuji;Kobayashi, Keisuke
研究了一种Cr2Ge2Te6(CRGT)相变材料。与传统的相变材料不同，它在低阻非晶相和高阻晶相之间表现出相反的电阻变化。此外，非晶态OCT中的反常低电阻率被认为是由于载流子密度过大所致，但其电输运机制尚不清楚。在本研究中，基于非晶态CRGT的电阻率、载流子密度、迁移率和电流-电压特性与温度的关系，讨论了非晶态CRGT的电输运机制。在300K以上，非晶态OCT的导电机制是热激活能带导电，这与传统的Ge-Sb-Te相变材料在非晶相中表现为Poole-Frenkel导电不同。在300K以下，非晶态CRGT呈现跳跃导电性，随温度的降低由变程跳跃(Mott VRH)转变为EFros-Shldovskii变程跳跃(ES-VRH)。在200K左右观察到了从Mott VRH到ES-VRH的交叉。此外，费米能级没有被钉扎在禁带中心，而是位于价带附近。
A Cr2Ge2Te6 (CrGT) phase change material (PCM) was studied. Different from conventional PCMs, it shows an inverse resistance change between a low-resistance amorphous phase and a high-resistance crystalline phase. Moreover, the anomalous low resistivity in the amorphous OCT is considered to be due to a large carrier density, but the mechanism of electrical transport is still not clear. In this study, the electrical transport mechanism of the amorphous CrGT was discussed based on the temperature dependence of the resistivity, carrier density, mobility, and current-voltage characteristics. Above 300K, the conduction mechanism of the amorphous OCT was thermally activated band conduction, which is different from the conventional Ge-Sb-Te PCMs that show Poole-Frenkel conduction in the amorphous phase. Below 300K, the amorphous CrGT shows hopping conduction, changing from variable range hopping (Mott VRH) to Efros-Shldovskii variable range hopping (ES-VRH) with decreasing temperature. The crossover from Mott VRH to ES-VRH was observed at around 200K. Furthermore, the Fermi level was not pinned at the center of bandgap; instead, it was located near the valence band.