Control of microstructures of semiconductor nanocrystals by ion implantation and their application for optical materials

自20世纪90年代初发现多孔硅的可见光致发光后，二氧化硅中嵌入的硅纳米晶体由于在室温下具有强烈的可见光致发光，在硅基光电子器件中具有潜在的应用前景，引起了人们的极大兴趣。近年来，由于在硅纳米晶体中观察到光的放大，对这种材料的关注大大增加。硅纳米晶体的制备方法多种多样，包括离子注入、CVD、溅射、MBE、激光烧蚀等技术。生产与传统微电子工艺兼容的硅纳米晶体最有前途的方法之一可能是离子注入。这种技术的优点是，通过改变影响和加速能量，可以将给定数量的离子置于可控的深度和分布。离子束合成硅纳米晶是制造更稳定、更纯净的硅纳米晶的潜在候选材料，可用于单片集成硅基光电器件。本文研究了快速热退火提高二氧化硅纳米晶光致发光性能的可能性。采用离子注入法制备了不同浓度的含硅过量SiO_2试样。在注入的样品中，硅析出形成纳米晶体是通过传统的炉内退火进行的。硅纳米晶体的光致发光强度和峰值发射能量取决于注入离子的影响。此外，与传统的炉内退火相比，快速热退火大大增强了发光强度。然而，在传统的炉内退火之后，快速热退火会使发光强度降低。结果表明，热处理顺序是影响发光强度的重要因素。此外，发现发光峰值能量依赖于，但很少，试样的热历史。基于实验结果，讨论了增强硅纳米晶体光致发光的机理，以及在SiO_2基体中通过离子注入和退火制备的包封硅纳米晶体的光致发光机理。少

After the discovery of the visible photoluminescence from porous silicon in the early 1990s, there has been considerable interest in Si nanocrystals embedded in of SiO_2 because of their potential applications toward Si-based optoelectronic devices due to their intense visible photoluminescence at room temperature. Recently, the attention to this material is greatly increased due to the observation of light amplification in Si nanocrystals. Si nanocrystals have been fabricated by a variety of methods and include such techniques as ion implantation, CVD, sputtering, MBE, laser ablation and so on. One of the most promising approaches to producing Si nanocrystals, compatible with conventional microelectronic processing, may be by ion implantation. This technique has the advantage that a given number of ions can be placed at a controlled depth and distribution by changing the fluences and acceleration energies. Ion beam synthesis of Si nanocrystals is a potential candidate for manufacturin … More g stable and pure Si nanocrystals for applications in monolithically integrated Si-based optoelectronic devices.In this work, potentialities of rapid thermal annealing to enhance the photoluminescence emission of Si nanocrystals in SiO_2 have been investigated. Ion implantation was used to synthesize specimens of SiO_2 containing excess Si with different concentrations. Si precipitation to form nanocrystals in implanted samples takes place with a conventional furnace anneal. The photoluminescence intensity and the peak energy of emission from Si nanocrystals depend on implanted ion fluence. Moreover, the luminescence intensity is strongly enhanced with a rapid thermal anneal prior to a conventional furnace anneal. The luminescence intensity, however, decreases with a rapid thermal anneal following a conventional furnace anneal. It is found that the order of heat treatment is an important factor in intensities of the luminescence. Moreover, the luminescence peak energy is found to be dependent, but a little, on thermal history of specimens. Based on our experimental results, we discussed about the mechanism of an enhancement of the photoluminescence, together with the mechanism of photoemission from encapsulated Si nanocrystals produced in a SiO_2 matrix by ion implantation and annealing. Less