Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen, Fujian, People's Republic of China.
Nanotechnology. 2010 Mar 19;21(11):115207. doi: 10.1088/0957-4484/21/11/115207. Epub 2010 Feb 24.
We directly demonstrate quantum-confined direct band transitions in the tensile strained Ge/SiGe multiple quantum wells grown on silicon substrates by room temperature photoluminescence. The tensile strained Ge/SiGe multiple quantum wells with various thicknesses of Ge well layers are grown on silicon substrates with a low temperature Ge buffer layer by ultrahigh vacuum chemical vapor deposition. The strain status, crystallographic, and surface morphology are systematically characterized by high-resolution transmission electron microscopy, atomic force microscopy, x-ray diffraction, and Raman spectroscopy. It is indicated that the photoluminescence peak energy of the tensile strained Ge/SiGe quantum wells shifts to higher energy with the reduction in thickness of Ge well layers. This blue shift of the luminescence peak energy can be quantitatively explained by the direct band transitions due to the quantum confinement effect at the Gamma point of the conduction band.
我们通过室温光致发光直接证明了在硅衬底上生长的拉伸应变 Ge/SiGe 多量子阱中量子限制的直接带间跃迁。通过超高真空化学气相沉积，在低温 Ge 缓冲层上的硅衬底上生长了具有不同厚度 Ge 阱层的拉伸应变 Ge/SiGe 多量子阱。通过高分辨率透射电子显微镜、原子力显微镜、X 射线衍射和拉曼光谱对应变状态、晶体学和表面形貌进行了系统表征。结果表明，拉伸应变 Ge/SiGe 量子阱的光致发光峰能量随 Ge 阱层厚度的减小而向高能移动。这种发光峰能量的蓝移可以通过导带 Gamma 点的量子限制直接带间跃迁来定量解释。
