NOVELTY - The method involves applying pressure in a range of 10-6000 MPa to an epitaxial film (20) grown on a substrate (10) e.g. sapphire blade substrate, through a vapor phase deposition process i.e. metal-organic chemical vapor deposition process, and an isostatic pressing or uniaxial pressing process. The epitaxial film is heated to temperature lower than melting temperature of the epitaxial film, where the substrate is made of a material selected from a group of sapphire, silicon carbide, gallium nitride and silicon, and the epitaxial film is made of gallium nitride or silicon.    USE - Annealing method for reducing defects e.g. line defects such as edge dislocations and screw dislocations, of an epitaxial film (claimed) for manufacturing an LED. Can also be used for reducing point defects such as vacancy defects, interstitial defects or impurities, planar defects such as stacking faults, and bulk defects such as voids or precipitates, and for production of an integrated circuit or fabrication of a solar cell.    ADVANTAGE - The method enables applying the pressure to the epitaxial film, so that lattice strain of the epitaxial film is reduced, thus effectively decreasing defect density of the epitaxial film. The pressure facilitates movement of atoms in the epitaxial film, so that the atoms are easily moved at the temperature to stable multiple lattice positions and the number of defects is lowered. The isostatic pressing process is selected, so that a set of pressure differences along directions received by the epitaxial film can be offset in a desired manner, thus applying higher pressure to the epitaxial film to reduced defect density without damaging the epitaxial film. The method enables accelerating movement of the defects to reduce defects density to a desired level in a shorter time period or at lower temperature. The method enables merely heating the epitaxial film without applying extra pressure to achieve lower defect density, thus improving quality of the epitaxial film after an annealing process.    DETAILED DESCRIPTION - The pressure is applied to the epitaxial film by using a pressure-transmitting medium selected from a group of graphite powder, hexagonal boron nitride powder, molybdenum disulfide powder, talc powder, pyrophyllite powder, lime powder, dolomite powder and salt. The epitaxial film is placed in an atmospheric environment containing gas selected from a group of nitrogen, mixture of nitrogen and hydrogen, argon, mixture of argon and hydrogen, and mixture of nitrogen and argon. An INDEPENDENT CLAIM is also included for an epitaxial film.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view illustrating an epitaxial film manufacturing process.    Substrate (10)    Epitaxial film (20)    Defects (21)