GaN-based lamb-wave mass-sensors on silicon substrates

Lamb-wave mass-sensors were fabricated with MOCVD-grown GaN-based thin films on silicon substrates. Crystalline GaN provides an alternative choice of material for fabricating Lamb-wave sensors. The advantageous properties of this material include high acoustic velocity, high chemical, mechanical and thermal stability, and the potential to integrate with a wide range of GaN-based devices such as high electron mobility transistor (HEMT) circuits, light emitting diodes (LED) and other photonic devices. We successfully developed GaN-based Lamb-wave mass-sensors in small size (membrane size of ∼1mm × 1mm). The sensors showed good signal strength and mass sensitivity, comparable to other mass-sensors using conventional materials. This novel approach not only allows robust low-cost sensors to be fabricated, but also enables future integration with generic GaN-based devices on the same chip (i.e. lab-on-a-chip).