High efficient photoluminescence from isoelectric impurities in quantum confined Si nanocrystals

这项工作的目的是通过同时掺杂n和p型杂质在硅纳米晶中形成等电陷阱。我们开发了一种制备P、B共掺Si纳米晶的方法，并详细研究了P、B掺杂浓度对其光学性质的影响。载流子补偿硅纳米晶的光致发光强度大于n型和p型杂质掺杂的硅纳米晶，有时甚至大于纯硅纳米晶的光致发光强度。此外，光致发光能量的可调谐范围被扩展到体硅晶体的带隙能量以下。通过适当控制硅纳米晶的杂质浓度和尺寸，光致发光能量可以控制在0.9 eV到1.5 eV之间，而不会有太大的强度损失。载流子补偿的硅纳米晶对稀土离子也是一种有效的光敏剂。研究表明，载流子补偿的硅纳米晶可以非常有效地激发附近放置的Er离子。Er离子在载流子补偿硅纳米晶中的光致发光强度大于纯硅纳米晶，虽然我们成功地证明了在硅纳米晶中形成等电心是可能的，并且这些纳米晶具有纯硅纳米晶所没有的特征，但杂质掺杂的硅纳米晶的电子结构仍然没有完全清楚。为了拓展硅纳米晶的功能并探索其应用，对其电子结构的深入了解是必不可少的，也将是未来研究的目标。

The purpose of this work is to form an isoelectric trap in Si nanocrystals by simultaneously doping n and p type impurities. We have developed a method to prepare P and B codoped Si nanocrystals, and studied the optical properties in detail as functions of P and B concentration. The photoluminescence intensity of carrier-compensated Si nanocrystals was larger than that of either n or p type impurity doped Si nanocrystals, and sometimes it was larger than that of pure Si nanocrystals. Furthermore, the tunable range of photoluminescence energy is extended to below the bandgap energy of bulk Si crystals. By properly controlling the impurity concentration and size of Si nanocrystals, the photoluminescence energy was controlled from 0.9eV to 1.5eV without losing the intensity so much. The carrier compensated Si nanocrystals also act as an efficient photo-sensitizer for rare-earth ions. It has been demonstrated that the carrier compensated Si nanocrystals can excite Er ions placed nearby quite efficiently. The photoluminescence intensity of Er ions in carrier-compensated Si nanocrystals was larger than that in pure Si nanocrystals.Although we could successfully demonstrate that the formation of isolectric centers in Si nanocrystals is possible and these nanocrystals exhibit characteristic features, which are absent in pure Si nanocrystals, the electronic structures of impurity doped Si nanocrystals are still not fully clarified. In order to extend the functionality of Si nanocrystals and explore the applications, deeper understanding of the electronic structures is indispensable, and will be a target of future research.