A conductivity-based selective etching for next generation GaN devices

Electrochemical etching having large selectivity based on the conductivity of n‐type GaN was investigated to demonstrate the feasibility of novel optical and microelectromechanical system devices. The electrochemical etching exhibited two regimes with different etching characteristics, i.e., nanoporous and electropolishing, depending on the doping concentration and applied voltage. For photonic applications, GaN microdisks and distributed Bragg reflectors were fabricated where optical index contrast can be achieved by selective etching or nanoporous formation of GaN. Stimulated emission of GaN microdisk was observed under pulsed optical pumping. In addition, a GaN cantilever was formed and its resonance frequency was measured at ∼120 kHz.