Analysis of GaInAsP Surfaces by Contact-Angle Measurement for Wafer Direct Bonding with Garnet Crystals

Abstract
GaInAsP surfaces with various treatments were analyzed by contact-angle measurement for wafer direct bonding between GaInAsP and garnet crystals. The contact angle of a water droplet was measured to estimate the hydrophilicity of the wafer surfaces. The most hydrophilic surface was obtained after an O2 plasma activation process. Direct bonding was successfully achieved between GaInAsP activated by O2 plasma and garnet crystals.