最後，為了能將量子點實際應用到VCSEL元件中，我們製作PIN二極體，驗證其電流特性，並生長符合本實驗量子點波段範圍的DBR結構，未來能夠以此基礎在量子點上下生長DBR並製作完整的VCSEL元件。 ;In this work, we investigate the effects of using InGaAsSb as a strain reducing layer for InAs quantum dots. Photoluminescence measurements reveal that the emission wavelength of quantum dots covered with an InGaAsSb strain reducing layer red-shifts as the indium and antimony compositions increase. However, their emission efficiency degrades when the compositions exceed a certain limit. Furthermore, low-temperature photoluminescence measurements show that the incorporation of antimony into the strain reducing layer raises the conduction band, increases the conduction band offset (ΔEc), and therefore reduces the probability of carrier escape at elevated temperatures, significantly enhancing emission intensity.
Next, we attempted to incorporate antimony into the quantum dots to form InAsSb quantum dots. However, the larger lattice constant of InAsSb increased the strain at the top of the quantum dots, causing the collapse of top of the quantum dots. Additionally, the surfactant effect of the antimony reduced the height of the quantum dots, causing a blueshift in emission wavelength. As an alternative, we employed a post-growth antimony soaking process to facilitate the exchange arsenic atoms with antimony atoms. This approach not only preserved the original shape of the quantum dots but also extended the emission wavelength to 1405 nm due to the narrower bandgap of InAsSb.
In this study, we fabricated PIN diodes with the InAsSb QDs as the active region. A distributed Bragg reflector (DBR) structure that matches the wavelength range of the quantum dots was also prepared. In the future, these foundations can be used to realize electrically pumped 1.4 m QD vertical cavity surface emitting lasers (VCSELs).
