Bandgap Engineering in OH-Functionalized Silicon Nanocrystals: Interplay between Surface Functionalization and Quantum Confinement
Bandgap Engineering in OH-Functionalized Silicon Nanocrystals: Interplay between Surface Functionalization and Quantum Confinement
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DOI：
10.1002/adfm.201701898
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发表时间：
2017-10-05
影响因子：
19
通讯作者：
Svrcek, Vladimir
中科院分区：
文献类型：
--
作者：
Burkle, Marius;Lozac'h, Mickael;Svrcek, Vladimir
在这项工作中，硅纳米晶体（Si-NC）的准带结构的第一性原理研究提供了一个系统的，重点是带隙工程相结合的量子限制的电子态与OH表面功能化。提供了带隙、Si-NC直径和氢氧化物覆盖度之间的映射，其可用作带隙工程的指导。作为第一性原理计算的补充，在量子限制机制中的Si-NC的光致发光（PL）波长被测量为具有1至4 nm之间的明确定义的直径。通过微等离子体技术制备Si-NC，其允许具有OH基团的Si-NC表面的无表面活性剂工程。微等离子体处理技术使我们能够逐渐改变OH覆盖的程度，从而使我们能够逐渐将PL光谱中的发射光转移至100 nm至更长的波长。的第一性原理计算是一致的实验观察到的波长上的OH覆盖率的依赖性，并表明，PL红移是由Si-NC和官能团之间的电荷转移，而另一方面，表面应变只起一小部分。
In this work, a systematic first-principles study of the quasi-band structure of silicon nanocrystals (Si-NCs) is provided, focusing on bandgap engineering by combining quantum confinement of the electronic states with OH surface-functionalization. A mapping between the bandgap, Si-NC diameter, and the degree of hydroxide coverage is provided, which can be used as a guideline for bandgap engineering. Complementary to first-principles calculations, the photoluminescence (PL) wavelength of Si-NCs in the quantum-confinement regime is measured with well-defined diameters between 1 and 4 nm. The Si-NCs are prepared by means of a microplasma technique, which allows a surfactant-free engineering of the Si-NCs surface with OH groups. The microplasma treatment technique allows us to gradually change the degree of OH coverage, enabling us, in turn, to gradually shift the emitted light in the PL spectra by up to 100 nm to longer wavelengths. The first-principles calculations are consistent with the experimentally observed dependence of the wavelengths on the OH coverage and show that the PL redshift is determined by the charge transfer between the Si-NC and the functional groups, while on the other hand surface strain plays only a minor part.