Studies on GaAsSb/GaAs type-II quantum well with an adjacent InAs quantum dot layer and its application to laser diodes
Date Issued
2010
Date
2010
Author(s)
Chu, Jang-Hsuan
Abstract
In this study, GaAs0.7Sb0.3/GaAs type-II quantum well lasers with an adjacent InAs quantum dot layer have been fabricated by gas-source molecular beam epitaxy. We found that the composite structure can decrease the threshold current density and the internal loss, and enhance the internal quantum efficiency, modal gain and characteristic temperature. We believe that the hole in quantum dots will tunnel into the quantum well, and the charged quantum dots could result in a potential fluctuation between the quantum dots and quantum well. The local confinement resulting from the potential fluctuation enhances the optical transition element, resulting in the aforementioned good performances. Increasing the Sb content of the composite structure from 30% to 34% makes the laser emission wavelength slightly red shift from 1200 nm to 1206 nm. However, the quality of GaAsSb quantum well becomes worse. From the room temperature PL of the laser samples, we found that the FWHM broadens from 93 nm to 113 nm when the Sb content increases from 30% to 34%, indicating the change of potential fluctuation between the quantum well and quantum dot. This change could result in the degradation of laser performances.
Subjects
quantum dot
quantum well
GaAsSb
type-II
laser
Type
thesis
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