Ge and Core/Shell Ge/Al Quantum Dot Lattices in Amorphous SiC Matrix for Application in Photo- and Thermosensitive Devices

Thin films with self-assembled quantum dots (QDs) featuring a semiconductor core and a metallic shell possess unique properties that can be precisely adjusted by altering the size, spacing, and structure of the QDs. In this study, we concentrate on the properties related to efficient photoelectric conversion and thermoelectric sensitivity of Ge and Ge/Al core/shell QD lattices within a SiC matrix. These nanostructured materials are fabricated by using the magnetron sputtering technique, which facilitates their formation and self-assembly during the deposition process. We explore various Ge QD sizes and Al shell thicknesses in films deposited on a p-type Si substrate. Our findings demonstrate that the optical, thermoelectric, and photoelectric conversion properties of these simple devices can be extensively tuned by modifying the core size and shell thickness. Notably, an enhanced photoelectric conversion of approximately 130% was observed in the material with the thinnest Al shell, explained by a theoretical model for electric field enhancement in core–shell structured QDs and multiple exciton generation, which is enhanced in nanoscaled Ge. Additionally, materials with Al-shell QDs exhibit a significantly high temperature coefficient of resistance, above 8%/K, surpassing that of Ge, SiC, or pure Ge QDs. These insights are vital for advancing and optimizing devices based on Ge QDs, offering valuable contributions to both QD physics and materials engineering. The materials produced hold great potential for applications in light-sensitive devices and temperature sensors.