6H碳化硅衬底上硅碳锗薄膜的生长特性研究

采用低压热壁化学气相沉积法,在6H-SiC衬底(0001)面上生长了不同温度(1100—1250℃),不同GeH₄流量比(6.3%—25%)的SiCGe薄膜样品,研究了SiCGe薄膜的表面形貌、生长特性以及样品中Ge组分含量的变化. 扫描电镜测试结果表明,SiCGe薄膜在低温下倾向于岛状生长模式,随着生长温度提高,岛状生长逐渐过渡到层状生长模式,同时伴有岛形状和密度的变化. X射线光电子能谱测试得出SiCGe样品中的Ge含量约为0.15％—0.62％,在其他参数不变的情况下,样品的G 关键词： 碳化硅 化学气相沉积 反相边界 岛状生长     

Island-growth of SiCGe films on SiC

SiCGe ternary alloys have been grown on SiC by hot-wall low-pressure chemical vapour deposition. It has been found that the samples cxhibit an island configuration, and the island growth of SiCGe epilayer depends on the processing parameters such as the growth temperature. When the growth temperature is comparatively low, the epilayer has two types of islands： onc is spherical island; another is cascading triangular island. With the increase of the growth temperature, the islands change from spherical to cascading triangular mode. The size and density of the islands depend on the growth duration and GeH4 flow-rate. A longer growth time and a larger GeH4 flow-rate can increase the size and density of the island in thc initial stage of the epitaxy. In our case, The optimal growth for a high density of uniform islands occurred at a growth temperature of 1100℃ for l-minute growth, with 10 SCCM GeH4, resulting in a narrow size distribution （about 30nm diameter） and high density （about 3.5 ×10^10 dots/cm2）. The growth follows Stranski- Krastanov modc （2D to 3D modc）, both of the islands and the 2D growth layer have face-centred cubic structure, and the critical thickness of the 2D growth layer is only 2.5 nm.[第一段]