Thermal Strain of In films deposited onto Si and GaAs Substrates

沉积在 Si 和 GaAs 衬底上的 In 薄膜的热应变

基本信息

批准号：
03452257
负责人：
MURAKAMI Masanori
金额：
$ 4.67万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03452257/
关键词：
thin film thermal strain In In X線回析

项目摘要

An investigation has been carried out of the thermal strain in In films deposited onto Si and GaAs substrates at 300k and 77k and then cooled down to temperatures as low as 20k. The strain in the In caused by differences in thermal expansion of In, and Si and GaAs was measured using X-ray diffraction techniques. Also the magnitude of the strain at 20k was found to approximate the strain value calculated from the difference in the thermal expansion coefficients using the biaxial strain model. For the In films, the crystallographic anisotropy both of the thermal expansion coefficient and Young's modulus was considered in calculations. The surface morphologies of In films evaporated in a vacuum of 10^<-7>-^<-6>were changed from island to continuous structures. The continuous films were obtained after that pre-evaporation of In was carried out in a vacuum chamber. Therefore, the change of film morphologies appeared to be caused by the oxygen concentration in the vacuum chamber. The thicknesses if In films were 100 to 140 nm. Since the thermal expansion coefficient of In film was greater than that of Si and GaAs substrates, compressive strain in the vertical direction of film was occurred according as the temperature was down room temperature to 20k. The measured and calculated strain values have a strong dependence on the crystal orientations. A large strain of -1.0%was obtained for (001) oriented grain and small strains of -0.6%were (111), (001) and (313) oriented grains. The dependence on the grain orientation of measured strain values was well agree with calculated strain values. Although the measured strain value were increased as the thickness of films decreased and films were more continuous, the measured strain values merely reached to -70%of the strain values expected by calculation. This mean that the film occurred the relaxation by plastic deformations.

对在 300k 和 77k 温度下沉积在 Si 和 GaAs 衬底上的 In 薄膜的热应变进行了研究，然后冷却至低至 20k 的温度。使用 X 射线衍射技术测量由 In、Si 和 GaAs 的热膨胀差异引起的 In 应变。此外，还发现 20k 时的应变大小近似于使用双轴应变模型根据热膨胀系数差异计算出的应变值。对于In薄膜，计算中考虑了热膨胀系数和杨氏模量的晶体各向异性。 10^-7-^-6真空中蒸发的In薄膜的表面形貌由岛状结构转变为连续结构。在真空室中进行In预蒸发后获得连续薄膜。因此，薄膜形貌的变化似乎是由真空室中的氧气浓度引起的。 In膜的厚度为100至140nm。由于In薄膜的热膨胀系数大于Si和GaAs衬底，当温度从室温降至20k时，薄膜垂直方向上会产生压缩应变。测量和计算的应变值对晶体取向有很强的依赖性。 (001)取向晶粒获得-1.0%的大应变，(111)、(001)和(313)取向晶粒获得-0.6%的小应变。测量的应变值对晶粒取向的依赖性与计算的应变值非常一致。虽然随着薄膜厚度的减小和薄膜更加连续，测量的应变值有所增加，但测量的应变值仅达到计算预期应变值的-70%。这意味着薄膜发生了塑性变形引起的松弛。