A method to enhance the optoelectronic properties of thin films containing three-dimensional ordered germanium quantum dots (QDs) coated with metal shell (Al, Ta, and Ti) in alumina matrix is presented. The conditions for the achievement of self-assembled growth of the metal-coated Ge QDs by magnetron sputtering deposition are explored. The influence of the metal shell on the structural, optical, and optoelectronic properties is found to be radical and desirable. First, it reduces Ge oxidation. Second, it enhances overall absorption by an order of magnitude. Third, it enables manipulation of the absorption curve shape in two ways. The Ge absorption peak, useful for photoelectric conversion, can be tuned significantly via control of the Ge energy gap because of the quantum confinement effect. On the other hand, infrared absorption can be controlled by the amount of metal because the geometry of the system can enhance absorption in the core by excitation of plasmon resonances in the shell. The mentioned effects result in a high increase of the photocurrent and quantum efficiency of core–shell nanoparticles compared to simple Ge particles. The experiments are supported by theoretical predictions, showing that the intensity of the incident radiation is strongly amplified in the region around the metal–semiconductor interface upon the excitation of plasmon resonances, hence increasing the probability of photon absorption and, thus, of charge carrier generation in the photo-active material. Therefore, the presented materials are very promising for photoelectric devices.

中文翻译：

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Ge量子点涂有嵌入氧化铝薄膜中的金属壳（Al，Ta和Ti），用于太阳能转换

提出了一种增强包含氧化铝基体中包覆有金属壳（Al，Ta和Ti）的三维有序锗量子点（QD）的薄膜的光电性能的方法。探索了通过磁控溅射沉积实现金属包覆的锗量子点自组装生长的条件。发现金属壳对结构，光学和光电性质的影响是根本的并且是期望的。首先，它减少了Ge的氧化。第二，它将整体吸收提高一个数量级。第三，它能够以两种方式操纵吸收曲线的形状。由于量子限制效应，可通过控制Ge能隙来显着调节可用于光电转换的Ge吸收峰。另一方面，红外吸收可以通过金属的量来控制，因为系统的几何形状可以通过激发壳中的等离子体共振来增强核心中的吸收。与简单的Ge粒子相比，上述效应导致核壳纳米粒子的光电流和量子效率大大提高。实验得到了理论预测的支持，表明在激发等离激元共振后，金属-半导体界面周围的区域中入射辐射的强度被强烈放大，从而增加了光子吸收的可能性，从而增加了载流子的产生在光敏材料中。因此，所提出的材料对于光电器件是非常有前途的。