Surface melting of gallium single crystals.
Surface melting of gallium single crystals.
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镓单晶的表面熔化。
DOI：
10.1103/physrevb.50.2529
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Bilgram
中科院分区：
文献类型：
--
作者：
Trittibach;Grütter;Bilgram
研究了Ga（010）、Ga（111）和Ga（112）表面的光学性质。单晶生长在超高真空条件下，并在原位椭偏技术已被应用。在低于体熔点Tm的温度下，在Ga（112）表面上观察到了准液态层的形成。该层的光学性质接近晶体体的光学性质。准液态层的厚度随温度T的升高而增加。Ga（112）表面准液层生长规律的函数特征与平均场理论的预言一致。在0.5< T_（m-T）<3.5K的温度范围内，膜厚的增加符合对数增长规律，相关长度为0.8± 0.2nm。当温度为0< T m-T< 0.2 K时，层厚的增加可以用幂律生长来描述，哈梅克常数W=（4.8±2.0）× 10− 18 mJ。在0.2< T_m-T<0.5K的温度范围内，该层的生长存在从对数生长到幂律生长的过渡。交叉厚度与无序或准液体层内的相关长度相当：lc *= 0.7± 0.1nm。Ga（010）和Ga（111）表面在Tm以下对热无序是稳定的。在Ga（010）表面观察到最高的稳定性。在Ga（111）表面上，当温度循环到体熔化温度时，已经检测到折射率的变化，而消光系数保持恒定。在熔点附近没有观察到n或k的剧烈变化，表明在Tm附近没有增强的无序发生。
Optical properties of the Ga (010), Ga (111), and Ga (112) surfaces have been studied. Single crystals have been grown at UHV conditions and in situ ellipsometric techniques have been applied. On the Ga (112) surface the formation of a quasiliquid layer has been detected at temperatures below the bulk melting point T m. The optical properties of the layer are close to the ones of the crystal bulk. The thickness of the quasiliquid layer increases with increasing temperature T. The functional character of the growth law of the quasiliquid layer of the Ga (112) surface is in agreement with the prediction of mean-field theory. In the temperature range 0.5< T m-T< 3.5 K the increase in layer thickness can be described by a logarithmic growth law with a correlation length ξ= 0.8±0.2 nm. For temperatures 0< T m-T< 0.2 K the increase in layer thickness can be described by a power-law growth with a Hamaker constant W=(4.8±2.0)× 10− 18 mJ. There is a crossover from a logarithmic to a power-law growth of the layer in the temperature range 0.2< T m-T< 0.5 K. The crossover thickness is comparable with the correlation length within the disordered or quasiliquid layer: l c*= 0.7±0.1 nm. Ga (010) and Ga (111) surfaces are stable against thermal disordering up to T m. The highest stability has been observed at the Ga (010) surface. On the Ga (111) surface, changes in the refractive index have been detected while cycling the temperature up to the bulk melting temperature, whereas the extinction coefficient remains constant. Close to the melting point no drastical changes in n or k have been observed indicating that no enhanced disordering takes place close to T m.