我们报导的一种单晶Si-Ge结构,可以当作在达到1.5μm波长范围工作的一种高效光电探测器使用。这种多层结构在一个3英寸的n型硅衬底上用分子束外延方法生长出的,包括以下几层:n~+硅(1000 ),n~+Ge_xSi_(1-x)合金(1800 ,从x=0到x=1分成10级)n～+锗(1.25μm),非掺杂的锗(2.0μm ),以及p~+锗(2500 )。上面三层形成一个锗p-i-n二极管,它通过一个高电导率的缓冲层,与Ge-Si界面隔开。这种结构的优点在于缓冲层中的材料缺陷不影响其性能。此外,用透射电子显微术检验表明,在Ge-Si界面处晶格失配引起的位错密度随着远离界面而减少。我们最初的几个实验结构的确其有锗p-i-n二极管的这种特性。其频谱响应曲线在室温和液氮温度下都与锗的文献中所给出的曲线相一致。对于1.45μm波长的入射光,在T=300K下我们测出其量子效率为40％。我们相信用我们这种方法展现了一个很吸引人的途径,这就是我们有在一个硅片上制造完整的红外装置的可能性。 We report a single-crystal Si-Ge structure that can be used as an efficient photodetector operating in the 1.5 μm wavelength range. This multilayer structure was grown by molecular beam epitaxy on a 3-inch n-type silicon substrate and consisted of the following layers: n ~ + silicon (1000), n ~ + Ge_xSi_ (1-x) , N ~ + germanium (1.25 μm), undoped germanium (2.0 μm), and p ~ + germanium (2500) are divided into 10 levels from x = 0 to x = 1. The top three layers form a germanium p-i-n diode that is separated from the Ge-Si interface by a high-conductivity buffer layer. The advantage of this structure is that the material defects in the buffer layer do not affect its performance. In addition, transmission electron microscopy revealed that dislocation density due to lattice mismatch at the Ge-Si interface decreased with distance from the interface. Our first few experimental structures did indeed have this characteristic of germanium p-i-n diodes. Its spectral response curve is consistent with the curves given in the literature for germanium at both room and liquid nitrogen temperatures. For the incident light with the wavelength of 1.45μm, we measured its quantum efficiency at 40% for T = 300K. We believe that this method of ours presents an appealing way that we have the possibility of making a complete infrared device on a silicon wafer.