PHOTON-ENHANCED WET OXIDATION AND ETCHING OF GaN

摘要

We report on the wet chemical oxidation and etching of unintentionally doped n-type gallium nitride (GaN) layers and quantum wells (QWs) grown on sapphire substrates. An ultraviolet (UV) enhanced photo-electro-chemical (PEC) process is observed when illuminated with a 253.7 nm mercury line source. A peak oxidation and etch rate of 224 nm/h and 125 nm/min, respectively, is observed in aqueous phosphorus acid (H_3PO_4) at a pH value of 3.5 and 0.75. Both of the oxidized GaN epilayer and InGaN quantum wells exhibit enhanced photocurrent and photo-luminescence response. The interface density of state (Dit), taken from a C-V analysis on a MIS diode structure, reveals a minimum value of D_(it,min) in < 3 x10~(11) cm~(-2)eV~(-1). These observations are attributed to the surface passivation effects due to the deep UV-enhanced wet oxidation on GaN.