Superlattice heterostructure of dislocation-free Ge quantum dots buried in Si spacer layers has been synthesized using ultra high vacuum-chemical vapor deposition technique. The heterostructure has been used as active layer in Si solar cells based upon vertical p-i-n junction configuration. Experiment shows that such solar cells exhibit strong repose to infrared radiation in contrast with the negligible response of solar cells with active layers of pure Si having the same thickness. A solar cell with 300 nm thick superlattice is shown to have thermodynamic efficiency of about 11.2%. This is correlated with the rather high quality of the heterostructure used in the present study as judged from photoluminescence spectroscopy and electron microscopy as well as strain and dark current measurements. It is concluded that such type of heterostructure may provide a pathway to develop efficient and cost effective solar cells.

利用超高真空化学气相沉积技术合成了埋在Si间隔层中的无位错Ge量子点的超晶格异质结构。基于垂直pin结配置，异质结构已被用作Si太阳能电池中的有源层。实验表明，与具有相同厚度的纯Si有源层的太阳能电池的响应可忽略不计，此类太阳能电池对红外辐射表现出强烈的抵抗力。具有300nm厚的超晶格的太阳能电池显示出具有约11.2％的热力学效率。从光致发光光谱和电子显微镜以及应变和暗电流测量结果来看，这与本研究中使用的较高质量的异质结构有关。