硫系相变材料Ge_1Sb_2Te_4和Ge_2Sb_2Te_5薄膜相变速度及电学输运性质研究

Study of Transition Speed and Electrical Transportation Properties of Ge_1Sb_2Te_4 and Ge_2Sb_2Te_5 Chalcogenide Phase-change Materials

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。

The Ge1Sb2Te4 and Ge2Sb2Te5 thin films were deposited by radio frequency magnetron sputtering. XRD measurement showed that with temperature increasing structure of Ge1Sb2Te, and Ge2Sb2Te5changed from amorphous to face-centered-cubic structure, and finally to hexagonal structure. Prom the results of XRD and resistance measurement, we got that Ge2Sb2Te5 crystallizes fast than Ge1Sb2Te4 and has a larger difference of resistance between amor- phous state and crystalline state. So Ge2Sb2Te5is more suitable for data storage. Measurement of Hall Effect gives the conclusion that conductivity of Ge1Sb2Te4 is dominated by Hall mobility and carrier concentration both, while conductivity of Ge2Sb2Te5is mainly dominated by carrier concentration.