AlGaN/GaN-based MEMS with two-dimensional electron gas for novel sensor applications

Novel microclectromechanical resonators structures have been realized based on AlGaN/GaN heterostructures, which provide a basis for sophisticated sensor structures. There were grown on SiC substrates confining a two dimensional eleotron gas (2PEG). By means of the developed etching technology, freestanding resonators were patterned without degrading the sheet carrier concentration and electron mobility of the 2DEG inside the beams, which was confirmed by electrical measurements before and after the various process steps. As actuation and read out principle magnetomotive and piezoelectric effects were used, respectively. Due to the high sensitivity of the 2DEG and the chemical stability of the utilized materials these structures are suitable for chemical and biological sensor applications, where the sensitivity of the 2DEG on the surrounding environment acts as additional sensing signal, for example for simultaneous measurements of the viscosity and pH - value of a nanoliter droplet.