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利用磁控溅射方法制备了Ge_1Sb_2Te_4和Ge_2Sb_2Te_5两种相变存贮材料的薄膜。原位X射线衍射(XRD)的结果表明,随着退火温度的升高,Ge_1Sb_2Te_4和Ge_2Sb_2Te_5薄膜都逐步晶化,材料结构发生了从非晶态到面心立方结构、再到六角密堆结构的转变。由衍射峰的半宽高可以看出,在达到第一次相变温度后,Ge_2Sb_2Te_5比Ge_1Sb_2Te_4结晶更快。原位变温电阻测量的结果显示,在相同的升温速率下,Ge_2Sb_2Te_5的热致晶化速率更快。而且Ge_2Sb_2Te_5非晶态与晶态的电阻差值更高。故Ge_2Sb_2Te_5比Ge_1Sb_2Te_4更适合作为相变存储器的材料。另外,对两种薄膜的电学输运性质进行了研究,霍尔效应的测量表明,Ge_1Sb_2Te_4材料电导的变化是迁移率和载流子浓度共同作用的结果,而Ge_2Sb_2Te_5材料电导的变化主要是由于载流子浓度的变化引起。
Thin films of two phase change memory materials, Ge_1Sb_2Te_4 and Ge_2Sb_2Te_5, were prepared by magnetron sputtering. The results of in-situ X-ray diffraction (XRD) show that the films of Ge_1Sb_2Te_4 and Ge_2Sb_2Te_5 gradually crystallize with the increase of annealing temperature, and the material structure changes from amorphous to face-centered cubic structure to hexagonal close-packed structure change. From the half width of the diffraction peak, it can be seen that Ge_2Sb_2Te_5 crystallizes faster than Ge_1Sb_2Te_4 after reaching the first phase transition temperature. In-situ resistance measurements showed that the thermal crystallization rate of Ge 2 Sb 2 Te 5 was faster at the same heating rate. And Ge 2 Sb 2 Te 5 amorphous and crystalline resistance difference is higher. Therefore, Ge_2Sb_2Te_5 is more suitable than Ge_1Sb_2Te_4 for phase change memory material. In addition, the electrical transport properties of the two films were investigated. The Hall effect measurements show that the change of conductance of Ge_1Sb_2Te_4 is the result of the combination of mobility and carrier concentration. The change of the conductance of Ge_2Sb_2Te_5 is mainly due to The change of the concentration of the atom is caused.