溅射功率对Ge_2Sb_2Te_5薄膜光学常数的影响

EFFECTS OF SPUTTERING POWER ON THE OPTICAL CONSTANTS OF Ge_2Sb_2Te_5 THIN FILMS

研究了溅射功率对 Ｇｅ２Ｓｂ２Ｔｅ５ 薄膜的光学常数与波长关系的影响，结果表明，在波长小于 ５００ｎｍ的情况下，随溅射功率的增加非晶态薄膜的折射率ｎ先增加然后减小，消光系数Ｋ则逐渐减小； 在波长大于 ５００ｎｍ的情况下，随溅射功率的增加折射率 ｎ逐渐减少，消光系数ｋ先减小后增加．对于晶 态薄膜样品，在整个波长范围折射率ｎ随溅射功率的增加先减小后增加，消光系数ｋ则逐渐减少．薄膜样 品的光学常数，在长波长范围随波长变化较大，在短波长范围变化较小．讨论了溅射功率对 Ｇｅ２Ｓｂ２Ｔｅ５ 薄膜的光学常数影响的机理．

The effects of sputtering power on the optical constants (n, k) of Ge2Sb2Te5 thin films in the wavelength range of 300-830nm were studied. The results showed that, for the amorphous thin films, the refractive index (n) first increases and then decreases with increasing sputtering power. whereas the extinction coefficient (k) decreases monotonically in the wavelength range of 300-500nm. In the wavelength range of 500-830nm, the refractive index (n) decreases with increasing sputtering power, while the extinction coefficient (k) first decreases and then increases. For the crystalline thin films, in the wavelength range of 300-830nm, the refractive index (n) first decreases and then increases, whereas the extinction coefficient (k) decreases with increasing sputtering power. The extent to which sputtering power influenced n and k changes with wavelength, it is greater in the long wavelength region than that in the short wavelength region. The mechanism by which the optical constants of the Ge2Sb2Te5 thin films are affected by sputtering power was discussed based on the variation of the density and microstructure of the films.