| Summary: | 碩士 === 國立中正大學 === 機械工程學系暨研究所 === 103 === This study aims to develop efficient light-emitting devices based on GeSn alloys. By increasing the Sn content in the material, the energy different between the direct and indirect conduction bands is significantly reduced, hence improving the light-emitting efficiency. Furthermore, this study presents an investigation into the use of thermal annealing and cavity structure to enhance the light emitting efficiency of GeSn alloys.
First, we employ thermal annealing to reduce the defect density in GeSn alloys caused by low-temperature growth. This annealing process also releases the compressive strain in the GeSn films, thus enhancing the light-emitting efficiency. Power-dependent photoluminescence experiments were performed on the GeSn samples under different thermal annealing temperatures. The results show that the photoluminescence efficiency can be improved via thermal annealing, and the optimal annealing temperature is 500℃.
For the GeSn light emitting devices, we fabricate GeSn waveguide resonant structures using lithography and reactive-ion etching. Clear waveguide modes were observed from room-temperature photoluminescence experiments. Furthermore, we employ Si3N4 stressor to introduce strain into GeSn films, and discuss the effect on light-emitting efficiency of GeSn alloys.
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