Growth of high quality Ge epitaxial films on Si substrate by low temperature buffer technique

采用低温缓冲层技术,在SI衬底上生长了质量优良的gE薄膜。利用原子力显微镜(AfM)、双晶X射线衍射(Xrd)和拉曼散射等研究了薄膜的晶体质量。结果表明,由于无法抑制三维岛状生长,低温gE缓冲层的表面是起伏的。然而,gE与SI间的压应变几乎完全弛豫。当缓冲层足够厚时,后续高温gE外延层的生长能够使粗糙的表面变得平整。在90 nM低温gE缓冲层上生长的210 nM高温gE外延层,表面粗糙度仅为1.2 nM,位错密度小于5x105CM-2,Xrd的峰形对称,峰值半高宽为460 ArC SEC。High-quality and thick Ge epitaxial films are grown on Si substrates utilizing the low-temperature(LT) buffer technique by ultrahigh vacuum chemical vapor deposition(UHV-CVD) and are characterized by atomic force microscope,X-ray diffraction,and Raman spectroscopy.The results show that the LT Ge buffer is rough due to the three-dimensional islands formations,but the misfit stress is nearly fully relaxed.Fortunately,the rough LT Ge surface is effectively smoothed by subsequent growth at elevated temperature when the LT Ge buffer is thick enough and the compressive strain is largely relaxed.Finally,the 210 nm Ge epitaxial film with smooth surface(root-mean-square roughness of 1.2 nm),low threading dislocation density(5×105 cm-2),and sharp and symmetric X-ray diffraction peak(full width at half maximum of ～460 arc sec) is achieved on LT Ge buffer with thickness of 90 nm.国家重点基础发展研究计划资助项目(2007CB613404

采用低温缓冲层技术在Si衬底上生长高质量Ge薄膜

采用低温缓冲层技术,在Si衬底上生长了质量优良的Ge薄膜。利用原子力显微镜(AFM)、双晶X射线衍射(XRD)和拉曼散射等研究了薄膜的晶体质量。结果表明,由于无法抑制三维岛状生长,低温Ge缓冲层的表面是起伏的。然而,Ge与Si间的压应变几乎完全弛豫。当缓冲层足够厚时,后续高温Ge外延层的生长能够使粗糙的表面变得平整。在90 nm低温Ge缓冲层上生长的210 nm高温Ge外延层,表面粗糙度仅为1.2 nm,位错密度小于5×105cm-2,XRD的峰形对称,峰值半高宽为460 arc sec

SOI基垂直入射Ge PIN光电探测器的研制

研制了在SOI衬底上工作于近红外波段的垂直入射GePIN光电探测器.采用低温Ge缓冲层技术,在超高真空化学气相淀积系统(UHV/CVD)上生长探测器材料.测试表明,器件的暗电流主要来源于表面漏电流,暗电流密度随着尺寸的增加而减小,在2V偏压时暗电流密度可达17.2mA/cm2;器件在波长1.31μm处的响应度高达0.22A/W,对应量子效率为20.8%.无偏压时,器件的响应光谱在1.2~1.6μm波长范围内观察到4个共振增强峰,分别位于1.25,1.35,1.45和1.55μm左右,峰值半高宽约为50nm,共振增强效应是由SOI衬底的高反射率引起的.采用传输矩阵法模拟的响应光谱与实验测量结果吻合良