Ge/Si量子点自组装结构增强材料光电性能的应用基础研究

Silicon is the main chip material for large scale integrated circuits, while the light-emitting efficiency is very low for the indirect bandgap, and due to the constant energy gap of 1.12 eV at room temperature, silicon shows diffcult to get photoelectric response in the middle and far infrared region and just transforms minority of solar energy on the photovoltaic generation. All of these have resulted in the low efficiency of Si-based optoeletronic devices. As to this, Ge/Si quantum dots which have discrete electron levels from the strong quantum confinement, are expected to be the new basic optoelectronic material, because the energy band can be tailored easily by changing the dot size, structure and distribution, and the charge carrier transport can be also enhanced as the same time. Our project proposes to prepare the ordered Ge/Si quantum dots with small size and high density, and build a variety of three-dimensional quantum structures with Ge quantum dot as zero-dimensional structural unit. By changing spatial symmetry of the quantum dots distributing in the array, the energy band will be regulated to extend the spectrum range of photoelectric response, and the kinetic carrier behaviors will also be manipulated to enhance the mobility and collection. Based on the measurements of light-emitting, spectrum response and energy conversion performance on the photovoltaic generaton, the efficient photo-electronic devices will be developed by the self-assembled structures of Ge/Si quantum dots.

硅是大规模集成电路的芯片材料，但是硅的间接带隙导致发光效率极低，硅在室温下的禁带宽度为1.12 eV，难以实现在中远红外波段的光电响应，和在太阳光谱范围内对光子能量充分利用，导致光电转换效率较低。Ge/Si量子点由于具有强量子限制效应和能级分立的特性，容易通过改变量子点的尺寸、结构和分布，调节能带，增强载流子的输运，有望成为高效硅基光电子器件的材料基础。项目研究高密度、小尺寸，分布均匀、有序的Ge/Si量子点的控制生长，以零维的量子点作为结构单元构筑空间点阵分布对称性不同的复杂量子结构，调节材料的能带，以改善光谱响应；操控光电作用过程中光生载流子的动力学行为，以增强载流子的迁移和收集，提高材料的发光性能和光电转换效率，为研制全硅基光电集成器件奠定基础。

项目针对Si材料发光效率低，难于实现中远红外光电响应的难题，研究有序Ge/Si量子点阵列的生长，应用能带工程裁剪材料的能带结构，增强硅材料的光电性能。项目通过离子束溅射生长得到密度高，尺寸小，且分布高度均匀有序的Ge/Si量子点阵列，指明在溅射生长Ge/Si量子点的过程中表面原子的热力学和动力学行为特征，实现了生长有序Ge/Si量子点的两种新方法；同时，在Ge/Si量子点材料中观察到无声子参与的激子发光峰，实现了量子限域效应对Si能带结构的调控；在此基础上，探索了Ge/Si量子点阵列在光电器件中的应用。此外，项目研究还探索了有序Si纳米线的制备及其对增强材料热电性能的作用，实现钙钛矿氧化物外延薄膜的制备及其超高的光电压响应。这些研究为实现高效的硅基光电材料提供了一条新的途径。项目研究发表论文4篇，其中1篇发表在SCI一区期刊；申请了发明专利13项，获得授权发明专利1项。