Development and Application of Bule Light-Emitting Nanocrystalline Si Materials

在硅纳米结构中，量子尺寸效应有望产生新的光学和电学性质，以取代现有的材料。这项研究的动机是开发这样的新材料和新器件。纳米晶硅（nc-Si）提供了一种将硅制成纳米尺度的方法。我们已经开发了一种成功的工艺来制造具有可控晶粒尺寸的nc-Si，并在室温下证明了nc-Si的蓝光发射。本项目的主要成果如下所示：(1)。利用铒作为成核中心，实现了在a-Si基体中形成的纳米硅晶体的纳米尺寸控制的蓝光发射。我们制作了一系列尺寸从3nm到10am的nc-Si样品。最小晶粒尺寸为2.7 nm，一个Si点包含。-l000原子。纳米硅层在晶体尺寸和光电性能上都是均匀的，在1.54 μ m处呈现蓝色发射带和尖峰，这是由壳层内的t引起的。我们发现，随着尺寸的减小，蓝色辐射向更高的能量偏移。位移值与吸收数据很好地吻合，可以用一种新的量子尺寸效应来解释。通过控制nc-Si的纳米晶尺寸，我们发现随着纳米晶尺寸的减小，nc-Si的吸收和反射光谱都向高能侧偏移。量子尺寸效应可以很好地解释这种位移，这种效应源于间接半导体Si的直接跃迁。nc-Si是一种具有尺寸可调的光学和电子特性的有前途的材料。为了理解nc-Si材料中电子的尺寸效应，提出了有序（nc-Si相）/无序（A - si相）量子点系统的新模型。理论计算表明，由于尺寸减小而对k-选择规则的修正增强了直接跃迁，从而导致蓝光发射，该模型计算的吸收和反射光谱均表现出尺寸效应，与实验结果吻合较好(4)。我们在Si衬底上制备了掺铒的nc-Si波导，并证明了其受激辐射为1.54。室温光泵浦下的Tm。这是实现全硅激光器的第一个突破。少

In Si nanostructures, quantum size effects are expected to give rise to new optical and electrical properties to replace present materials. The motivation of this study is to develop such new materials and new devices. Nanocrystalline Si (nc-Si) provides a way to fabricate Si into am scale. We have developed a successful process to fabricate nc-Si with controllable crystallite sizes and demonstrated a blue light emission from nc-Si at room temperature. Main results of this project are shown in bellow.(1).Size-dependent blue light emission from nc-SiSize control of Si nanocrystallites formed in a-Si matrix is achieved by using Er as a nucleation center. We have fabricated a series of nc-Si samples with size from 3 nm to 10 am. The smallest crystallite size was 2.7 nm, a Si dot including .-l000 atoms. The nc-Si layers are homogeneous both in the crystallite size and in the optoelectronic properties and show a blue emission band and a sharp peak at 1.54mum which is caused by intra-shell t … More ransitions in Er atoms up to room temperature. We showed that the blue emission shift to higher energies with decreasing size. The value of the shift is in good agreement with the absorption data and could be explained by a novel quantum size effect.(2).First evidence of quantum size effect in ne-SiBy controlling the nanocrystallite size of nc-Si, we demonstrated that both the absorption and reflection spectra of nc-Si shift to higher energy side with decreasing crystallite size. The shift was well explained by the quantum size effect which originates direct transitions in the indirect semiconductor Si. The nc-Si is a promising material with size-tunable optical and electronic properties.(3).A new model of nc-Si/a-Si quantum dot systemWe proposed a new model of order (nc-Si phase)/disorder (a-Si phase) quantum dots system to understand the size effect of electrons in nc-Si materials. A theoretical calculation indicates that direct transitions enhanced by a modification of k-selection rules due to the size reduction result in the blue light emission, Both the absorption and reflection spectra calculated by the proposed model show size effect and are in good agreement with our experimental results.(4).An Er-doped nc-Si laser operated at room temperatureWe have fabricated Er-doped nc-Si waveguides on Si substrates and demonstrated a stimulated emission at 1.54 .tm at room temperature under optical pumping. This is the first breakthrough of realizing an all-Si laser. Less