What chemical reactions yield GaN film from Ga2O3?

Dear Mr. Ted,
First of all, I'd like to beg apology if there's any mistake in my English. I'm a Physics Department student. I have a project of making GaN film. But there's some problems. I use Ga2O3, citric acid ⇦ on eBay or Amazon [affil link] (C6H8O7),NH4OH and for aqua regia I use HCl and HNO3 -- but I can't find the reaction for Ga2O3+HCl+HNO3+C6H8O7? Could you help me, please?

Your English is excellent, Lulu! Unfortunately your question is totally unfamiliar to me though. I hope someone who is involved in that area can help.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

See 'Synthesis of gallium nitride films by a novel electrodeposition route,' R.K. Roy and A.K. Pal, Materials Letters, Volume 59, pages 2204-2209 (July 2005). From the abstract (available on-line):
"Gallium nitride films were deposited onto SnO2-coated glass substrates by an electrodeposition technique. A mixture of gallium nitrate, ammonium nitrate and water was utilized as electrolyte for the above. The applied voltage between the electrodes was ~7 V for the deposition of gallium nitride films."

GaN films are usually deposited at high temperatures by either decomposition of metallorganic vapors (MOCVD) or reactive sputtering in nitrogen-containing atmospheres (reactive PVD). It is highly unusual to be able to form GaN in the presence of water. It is also perhaps not practical to deposit anything from aqueous solution at 7 volts. Perhaps recover hydrogen at the cathode?