This dissertation explores the design, fabrication, and characterization of photodetector-integrated vertical cavity surface emitting lasers(VCSELs), which consist of oxide-apertured monitor photodetectors and 780 nm deutron-implanted VCSELs or 850 nm oxide-confined VCSELs. First, the key design and fabrication issues on the VCSELs are reviewed and the characteristics of the VCSELs are investigated. Both kinds of VCSELs show over 2 mW of laser power and under 7 mA of threshold current, which indicates both the VCSELs are modelately good to be integrated with the oxide-apertured photodetectors. Also the dissertation demonstrates in situ interferometry for thickness calibration for KAIST MOCVD system. It gives less than 1 % of epi-layer thickness error and therefore it will be useful for the growth of integrated photodetector.
Next the oxide-apertured photodetectors integrated with VCSELs are designed and fabricated. The photocurrent originating from spontaneous emission is suppressed by more than a factor of 10 in the oxide-apertured photodetector on the implanted VCSEL owing to the use of nonradiative recombination at the GaAs/oxide interface. In addition, the unavoidable internal loss from the detector is minimized by locating the GaAs detection layer as far as possible from the VCSEL cavity.
For the oxide-apertured photodetectors on the 850 nm oxide-confined VCSELs, the effect of the spontaneous emission is relatively minimized due to the very low threshold current and the very high efficiency of the VCSELs. For the temperature change of 30℃, the oxide-apertured photodetector with the oxide aperture of 10 μm shows the photocurrent change of less than 5% from spontaneous emission and, in contrast, the photodetector without the oxide aperture gives that of more than 10% . It demonstrates the photodetector with oxide aperture is superior to that without oxide aperture for the fluctuation of laser operation environment.
In conclusion, the oxide-apertured photodetector has a simple growth and fabrication process and shows the spontaneous emission photocurrent of less than 10 μA, which opens the possibility that the oxide-apertured device will be useful for the industrial use.