Improved spectral response of an InAs QD RC-SACM-APD with Ta2O5/SiO2 DBRs

We report the improvement in the spectral response of an InAs QD resonant-cavity separate absorption, charge, and multiplication avalanche photodetector (RC-SACM-APD) by increasing the quantum efficiency (QE) using dielectric Ta₂O₅/SiO₂ top distributed Bragg reflectors (DBRs). The reflectivities of the top and bottom DBRs were numerically designed to be 70 % and 99.1 %, respectively, in order to maximize the QE. The spectral response characteristics of the InAs QD RC-SACM-APD with enhanced top DBRs was remarkably improved at 1098 nm, which is close to the target wavelength of 1100 nm, and its full width at half-maximum (FWHM) was 19 nm. The photoluminescence (PL) spectra revealed an intense and narrow single-mode peak at 1101 nm. The FWHM of the PL peak was as narrow as 8 nm and the difference in wavelength between the spectrum and the PL peak was as small as 3 nm.