Bandgap wavelength shift in quantum well intermixing using different SiO2 masks for photonic integration

As a photonic integration method of semiconductor membrane structure, quantum-well-intermixing (QWI) process using O₂-sputtered SiO₂ mask was investigated by comparing the photoluminescence peak wavelength shift between two sections with/without the SiO₂ mask. As the result, a large bandgap wavelength difference of 80 nm (47 meV) was obtained while quite large transient region (90 μm) was observed. Since this fact was considered to be attributed to the temperature gradient along the masked and window regions during the rapid thermal annealing (RTA) process, we deposited CVD SiO₂ (which has smaller vacancies than O₂-sputtered SiO₂ hence the bandgap wavelength shift is smaller) on the entire surface after forming O₂-sputtered SiO₂ mask pattern and successfully reduced the transient region length to less than 5 μm.