Semiconductor microlenses fabricated by one-step wet etching

We fabricated refractive semiconductor microlenses using a diffusion-limite d chemical etching technique based on Br-2 solution. The simple one-step we t etching process produced high-quality microlenses of GaAs and InP, the tw o most popular compound semiconductor materials used in optoelectronics. A spherical GaAs microlens with a nominal lens diameter of 30 mu m exhibited a radius of curvature and focal length of 91 and 36 mu m, respectively. The surface roughness, examined by atomic force microscopy (AFM), was measured to be below +/-10 Angstrom. This microlens fabrication method should be re adily applicable due to the simplicity in processing and the high-quality r esults.