Selective Dry Etching of (Sc_20_3)_x(Ga_20_3)_(1-x)Gate Dielectrics and Surface Passivation Films on GaN

摘要

(Sc_2O_3)_x(Ga_2O_3)_(1-x)films grown by molecular beam epitaxy show promise for use as surface passivation layers and gate dielectrics on GaN-based high elec-tron mobility transistors.Completely selective,low-damage,dry etching of (Sc_2O_3)_x(Ga_2O_3)_(1-x)films with respect to GaN can be achieved with low-power inductively coupled plasmas of CH_4H-2/Ar with etch rates in the range 200-300 A/min.The incident ion energies are of order 100 eV,and no roughening of the underlying GaN was observed under these conditions.Similar etch rates were obtained with Cl_2/Ar discharges under the same conditions,but GaN showed rates almost an order of magnitude higher.