在室温、10 Pa氦气氛围中，采用脉冲激光沉积（PLD）技术，通过在烧蚀羽辉正上方距靶面不同位置垂直引入一束氦气流，在烧蚀点正下方与烧蚀羽辉轴线平行放置的衬底上沉积了一系列纳米Si晶薄膜。扫描电子显微镜（SEM）、拉曼（Raman）散射光谱和X射线衍射（XRD）谱检测结果均表明，纳米Si晶粒在距靶一定的范围内形成，其尺寸随与靶面距离的增加先增大后减小。在分析衬底上的晶粒尺寸及其位置分布的基础上，结合流体力学模型、成核分区模型、热动力学方程以及晶粒形成后的类平抛运动，计算得出了纳米Si晶粒的成核区宽度为56.2 mm。

The crystalline Si films are prepared by pulsed laser deposition (PLD) in 10 Pa helium gas at room temperature. In experiments, substrates are located under ablated spot and paralleled to the axis of plume, at the same time, a vertical extra helium gas flow apart different distance from target surface is introduced above plume. The results of scaning electron microscope (SEM), Raman scattering and X-ray diffraction (XRD) indicate that nano-crystal grains formed in one area apart from target, the sizes first increase and then decrease with the addition distance from target surface. Size and position distribution of grains on substrates are analyzed. Combing with hydrodynamics model, nucleation division model, thermokinetic equation and rule of flat parabolic motion-like after formation of grains, nulcleation region width of 56.2 mm is calculated through numerical calculations.