Experimental demonstration and observation of a plasmon wave occuring at a GaAs-Au-GaN interface.

Integration of surface plasmon structures using semiconductor materials is limited due to the difficulties encountered in maintaining the resonance conditions upon packaging. We propose here a technology process allowing us to bond two semiconductors, such as gallium nitride (GaN) and gallium arsenide (GaAs), through a thin metal layer. This solution allows the excitation of a surface plasmon wave in an integrated classical Kretschmann configuration. The Letter presents various metal bonding conditions employed for Au deposited on both GaN/sapphire and GaAs substrates aiming at semiconductor-metal-semiconductor interfaces transparent at telecom wavelengths. The process conditions for the bondings are optimized using Ti/Au (3 nm/30 nm) layers on each of the wafers to be bonded under an applied pressure of 500 mbar at a low temperature of 250°C.