热处理对GeSb_2Te_4薄膜微观结构及其摩擦性能的影响

Effect of Heat-treatment on Microstructure and Frictional Properties of GeSb_2Te_4 Thin Films

利用射频溅射法制备了GeSb2Te4薄膜并对其进行热处理,分析热处理前后样品的结晶情况,用纳米硬度计测定硬度,利用静电力显微镜表征样品的表面电势,采用原子力显微镜观察薄膜表面形貌,利用侧向力显微镜对比考察了在考虑相对湿度的情况下,热处理前后GeSb2Te4薄膜的粘附力和摩擦性能.结果表明:经过退火的沉积态GeSb2Te4薄膜发生从非晶相到fcc亚稳相再到hex稳定相转变;粘附力与表面粗糙度之间没有明显的对应关系,但与样品表面自由能和表面电势有一定关系;在低载荷下GeSb2Te4薄膜的摩擦力很大程度上受粘附力支配,而在高载荷下的摩擦力受犁沟影响显著;经过340℃退火GeSb2Te4薄膜由于具有层状结构,呈现出一定的润滑作用.

GeSb2Te4 films were deposited by RF magnetron sputtering, and two samples were annealed at 200℃ and 340℃ in vacuum, respectively. Morphology and phase structure were analyzed by AFM and XRD techniques, and their hardness was also measured with a nanoindenter. A lateral force microscope （LFM） was used to investigate the adhesion and friction behavior of GeSb2Te4 thin films before and after annealing under different relative humidity. Besides, their surface potential was also evaluated with the electric force microscopy（EFM）. It was found that the deposited GeSb2Te4 thin film undergoes the transition from amorphous ,to metastable fcc structure and then to a more stable hex structure. The adhesion has a weaker relationship with surface roughness, but a certain correlation with surface free energy and surface potential of GeSb2Te4 thin films. And the friction behavior of GeSb2Te4 thin films follows their adhesion behavior under lower applied load. However, such a relation becomes less significant when the load is relatively higher. Accordingly, the mechanical behavior, especially the plow effect, plays a leading role. Moreover, the GeSb2Te4 thin film annealed at 340℃ had a layer structure and it played the role of lubrication.