Fabrication of GaAs-microlens by using diffusion-limited wet etching

Abstract

Microlens can be used to realize high power and single transverse mode by forming a compound cavity with p-DBR and n-DBR of the vertical cavity surface emitting laser (VCSEL) chip. Microlenses with different diameters are fabricated on the n-side of the VCSEL wafer by using diffusion-limited wet etching. With the diameter of 600 μm, the roughness of the lens surface is 15.55 nm, the curvature radius is 959.66 μm, the focal length is 369.1 μm. With the smaller diameter of 200 μm, the roughness of the lens surface is 12.56 nm, the curvature radius is 959.86 μm, the focal length is 369.18 μm. The solution ratio of HBr, H2O2, H2O is the major factor to impact the etching rate. Also the temperature of environment is the important factor to form the smooth surface of lens. Show more