激光辐照引起Ge_2Sb_2Te_5非晶态薄膜的电/光性质变化

Laser Induced Change in the Electrical and Optical Properties of Amorphous Ge_2Sb_2Te_5 Thin Films

研究了激光辐照引起Ge2Sb2Te5非晶态薄膜的电/光性质变化,当激光功率为580mW时薄膜的方块电阻有四个数量级（10^7～10^3Ω/□）的突变;对电阻发生突变前、中、后的三个样品进行了XRD测试,结果表明,随着激光功率的增大,薄膜由非晶态向晶态转变,用椭偏仪测试了结构转变前、中、后三个样品的光学常数,在可见光范围内薄膜的光学常数在波长相同情况下有：n（非晶态）〉n（中间态）〉n（晶态）,k（晶态）〉k（中间态）〉k（非晶态）,α（晶态）〉α（中间态）〉α（非晶态）,结合电阻变化曲线和XRD图谱讨论了激光辐照Ge2Sb2Te5非晶态薄膜的电/光性质变化同激光功率和结构转变之间的关系.

Sheet resistance of laser-irradiated amorphous Ge2Sb2Te5 thin films prepared by magnetron sputtering were measured by the four-point probe method.With the laser power increasing,the sheet resistance undergoes an abrupt change of four orders of magnitude（107-103Ω/□）at about 580mW. X-ray diffraction studies of the three samples before,at and after the abruption point reveal the phase change process of the Ge2Sb2Te5 thin films from amorphous to crystal states.Optical constants of the three samples measured by ellipsometry have relations as follows,n（amorphous）〉n（intermediate）〉n（crystalline）,k（crystalline）〉k（intermediate）〉k（amorphous）,α（crystalline）〉α（intermediate）〉α（amorphous）.Based on the above results,the relationship between the electrical/optical properties and the structural state of the Ge2Sb2Te5 thin films is discussed.