Graphene Membranes for Hall Sensors and Microphones Integrated with CMOS-Compatible Processes

Graphene is a promising candidate for future electronic devices because of its outstanding electronic and mechanical properties. The high charge carrier mobility in graphene, particularly in substrate-free suspended form, suggests applications as Hall effect sensors. In addition, graphene membranes are highly desirable as pressure sensors or microphones. Here, suitable integration processes for freestanding graphene devices with standard CMOS processes are demonstrated. We propose a process flow for graphene membrane-based Hall sensors and microphones that is CMOS back end of the line compatible. The Hall sensors show mobilities up to 11900 cm2 V–1 s–1, which are higher than in germanium- and GaAs-based Hall sensors. Graphene-based microphones are resonance-free for frequencies up to 700 kHz, i.e., in the acoustic wave region, which is a unique advantage over conventional microelectromechanical (MEMS) microphones.