在衬底加热条件下利用磁控溅射法制备Ge_2Sb_2Te_5薄膜,利用X射线衍射仪表征各种沉积温度下薄膜的结构,差示扫描量热法(DSC)确定的薄膜晶化温度为168℃(加热升温速率为5℃/min).用四探针法测试薄膜的方块电阻,分光光度计测试薄膜的反射率谱,并根据反射率数据讨论在波长为405和650 nm时薄膜的反射率对比度同沉积温度关系.结果表明:室温沉积的薄膜为非晶态:在衬底温度为140℃条件下薄膜已完全转变为晶态Ge_2Sb_2Te_5,在300℃时出现少量的六方相:低于140℃时易形成非Ge_2Sb_2Te_5组分的其它晶相,它们对薄膜的电/光性质有很大的影响,可能是导致此类相变光存储薄膜使用过程中反射率对比度下降的原因.
Using magnetron sputtering method the Ge_2Sb_2Te_5 films were deposited at different substrata temperatures (from room temperature to 300 ℃) on Si substrata. The structure and the crystallization ternperature of the films were determined by X-ray diffraction and Differential Scanning Calorimeter, respectively. The electrical resistance and the reflectivity of the films were measured with a four-point probe and ultraviolet photo-spectrometer, respectively. Based on the reflectivity of the films, it is found that the refieetivity contrasts of the Ge_2Sb_2Te_5 films at the wavelengths of 405 and 650 nm change with the substrata temperature. The films prepared at room temperature are amorphous, and crystalline (fcc) at 140 ℃, and a little hexagonal (hex) structure comes forth at 300℃. At 140 ℃ the phase separation may take place, and exhibits significant influence on the electrical and optical properties.
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