In Situ Center Wavelength Control of AlInN/GaN Distributed Bragg Reflectors with In Situ Reflectivity Spectra Measurements

An in situ control of a center wavelength in a 40‐pair AlInN/GaN distributed Bragg reflector (DBR) for GaN‐based vertical‐cavity surface‐emitting lasers (VCSELs) with an in situ reflectivity spectra measurement is proposed and developed. A procedure of the in situ control consists of the following three steps: 1) to grow an initial 5‐pair DBR; 2) to obtain the center wavelength value just after the initial DBR growth by the in situ reflectivity spectra measurement; and 3) to adjust growth times as a result of the obtained center wavelength value and continue the remaining 35‐pair DBR. It is experimentally demonstrated that the in situ control of the center wavelength in the 40‐pair DBRs with the ±2% thickness deviations in the initial 5‐pair DBR results in reductions of the deviation down to ±0.3%. The in situ DBR center wavelength control is a key technique for highly reproducible GaN‐based VCSELs.