Strain relaxation in AlN/GaN bilayer films grown on γ-LiAlO2(100) for nanoelectromechanical systems

We fabricate submicrometer-wide cantilevers and beams from M-plane AlN/GaN bilayer films grown on γ-LiAlO2(100) substrates. The chemically reactive substrate is ideal for fabrication of nanoelectromechanical systems using the light, stiff, and piezoelectrically active AlN. The absence of polarization fields in M-plane quantum wells allows us to incorporate optical functionalities in the (Al,Ga)N-based nanoelectromechanical systems. Self-rolling of the cantilevers indicates that the bilayer films are strained at the AlN–GaN interface along the a axis, whereas the strain is roughly completely relaxed along the c axis. We examine the partial relaxation of the strain along the a axis when the layer thickness is varied.