绿色激光退火对多晶锗硅薄膜特性的影响

Influence of Green Laser Annealing on the Properties of Polycrystalline Silicon-Germanium Thin Film

随着板上系统技术的发展,在较低温度下制备具有高空穴迁移率的多晶锗硅(Si Ge)薄膜具有重要的研究意义。使用波长为532 nm的绿色脉冲式激光器对多晶Si Ge薄膜进行了退火处理,并对薄膜的特性变化进行了表征。经过优化,在单脉冲激光能量为0.5 m J和10 mm/s的扫描速度下,薄膜的特性有了较大的提高。与未经过处理的薄膜相比,退火后薄膜的晶粒尺寸增大了3倍,空穴霍尔迁移率提高了4.75倍,载流子浓度提高了24.6倍,从而使薄膜的电阻率减小了两个数量级。同时,薄膜的表面形貌也有改善,表面粗糙度的均方根值从11.54 nm降低至4.75 nm。结果表明,激光退火过程中薄膜"熔化-再结晶"的过程可以显著减小晶粒中的缺陷和晶界的数量,进而改善薄膜的电学特性。因此,绿色激光退火技术在高性能多晶Si Ge薄膜晶体管制备中具有潜在的应用价值。

As the development of system on panel（ SOP）,the preparation of polycrystalline Si Ge（ poly-Si Ge） film with high hole mobility at low temperature is of great significance. Poly-Si Ge thin lms were annealed using a pulsed green laser（ λ = 532 nm）,and its properties were characterized. After optimization,the properties of the films have been greatly improved with the single pulse laser energy of0. 5 m J and the scanning speed of 10 mms. Compared with the as-grown poly-Si Ge,the grain size of the annealed sample was tripled,the hole Hall mobility and the carrier concentration were increased4. 75 and 24. 6 times,respectively. Consequently,the resistivity was 2 orders of magnitude smaller than the as-grown counterpart. In addition,the surface topography and roughness of the film were also improved,with the root-mean-square value of the surface roughness reduced from 11. 54 nm to 4. 75 nm.The results show that due to the melt and recrystallization process during the laser annealing,the numbers of the defect density and grain boundary are extensively reduced. Thus,the green laser annealing is a promising technology for high performance poly-Si Ge thin film transistor devices.