to 100 u00b0 c in an inert atmosphere the etchant solution may also include other acids group iii nitride semiconductor devices cleaned in this manner require lower driving voltages than devices cleaned with prior art methods application_number US 1877698 A description the present invention is based on the experimental observation that hydrofluoric acid etchant systems such as those used for forming mirror surfaces on a silicon based semiconductor act as an effective etchant for group iii nitride semiconductors the method of the present invention can be applied to group iii nitride semiconductors such as semiconductors based on gan aln algan and gainn the hydrofluoric acid system etchant of the present invention utilizes hydrofluoric acid or an acid mixture containing hydrofluoric acid for example the hydrofluoric acid may be mixed with nitric acid or hydrochloric acid the manner in which a group iii nitride semiconductor surface is cleaned by the method of the present invention involves four steps first the surface of the semiconductor is cleaned with an organic solvent based solution the preferred organic solvents are trichloroethylene acetone methanol or isopropanol these compounds may be used independently or in combinations of two or more cleaning methods based on such organic solvents are well known in the semiconductor arts and hence will not be discussed in detail here next the semiconductor surface is rinsed with water purified water generated by ion exchange or distillation is preferred such rinsing procedures are well known in the semiconductor arts and hence will not be discussed in detail here third the semiconductor is then subjected to a hydrofluoric acid based etchant the hydrofluoric acid is preferably applied in an aqueous solution at a concentration greater than 5 however the concentration is not critical if the concentration is too low the time needed to.