Critical aspects of VCSELs fabrication

High requirements for VCSEL fabrication are essential for enhancing functionality, like increasing optical output power, maximum operating temperature, and reducing threshold current. Processing includes several critical steps, like: contact formation, plasma etching of mesa, passivation and oxidation. An ICP-RIE plasma etching procedure was developed, including the composition and flow of process gases, pressure, power and temperature, which allowed to obtain the desired trapezoidal profile of the mesa walls. A SiO2 passivation layer was also used, which, combined with new etching conditions, allowed to develop of a simplified VCSEL fabrication method with contact from the bottom of the sample and a more shallow mesa.