Ge-rich GeSbTe (GST) alloys are attracting Phase Change Materials for future memories as their higher crystallization temperature offers an extended range of applications. We have studied the electrical characteristics of PCM cells using such alloys as active layers. We show by impedance spectroscopy that the cells in the RESET (amorphous) state are not only resistive but also exhibit a capacitive component. Although trap-assisted conduction models are apparently able to describe the I(V) and I(T) characteristics of the devices in this state, their physical background is thus questionable. Alternatively, we show that granular models, describing electrical transport through conductive grains separated by insulating interfaces, are also able to simulate these characteristics, while fed by physically sound fitting parameters. Moreover, we show that the SET (crystalline) state is not simply ohmic but that its characteristics, as conductive as a metal but reacting as an insulator to temperature, resemble to those found in a semiconductor doped with a very low ionization energy defect. Finally, all these characteristics can be understood by considering that the electrical properties of cells made of Ge-rich GST layers are not those characteristic of some defective and homogeneous material but instead result from strong chemical heterogeneities found both in the amorphous and crystalline states of these Ge-rich alloys.

富含锗的GeSbTe（GST）合金吸引了相变材料以备将来使用，因为它们较高的结晶温度提供了广泛的应用范围。我们已经研究了使用这种合金作为活性层的PCM电池的电学特性。我们通过阻抗光谱法表明，处于RESET（非晶）状态的单元不仅具有电阻性，而且还具有电容性成分。尽管陷阱辅助传导模型显然能够描述这种状态下器件的I（V）和I（T）特性，但是其物理背景仍然值得商question。或者，我们显示出描述通过绝缘界面分开的导电颗粒进行电传输的颗粒模型，在通过物理上合理的拟合参数馈电的同时，也能够模拟这些特性。此外，我们表明，SET（晶体）状态不仅是欧姆状态，而且它的特性（如金属一样导电，但对温度起绝缘子的作用）类似于在掺杂了非常低电离能缺陷的半导体中发现的特性。最后，可以通过考虑由富Ge的GST层制成的电池的电性能不是某些缺陷和均质材料的那些特性来理解所有这些特性，而是由这些非晶态和结晶态中发现的强烈化学异质性导致的富含锗的合金。