White light was obtained by mixing blue light from the emission of a gallium nitride ͑GaN͒ chip and yellow light from the fluorescence of a Y 3 Al 5 O 12 :Ce 0.05 yellow phosphor. A uniform coating and an optimized thickness of yellow phosphor layer on a GaN chip were necessary for achieving an efficient white light emitting diode. The phosphor particles were coated on a GaN chip or indium tin oxide by several methods including the slurry method, the settling method, and electrophoretic deposition ͑EPD͒. The properties of the phosphor layers prepared by these methods were examined using scanning electron microscope and photoluminescence. The chromaticity of white light was dependent upon the thickness of the phosphor layer. The properties of the phosphor layer prepared by EPD such as packing density, thickness, and uniformity could be more easily controlled than those by the slurry and settling methods. Further high packing density of the EPD could compensate for the typical thick phosphor layer, allowing the thin layer to be fabricated. To overcome the weak adhesion strength of phosphor particles by the EPD, an aqueous solution including poly͑vinyl alcohol͒ ϩ ammonium dichromate was coated on the phosphor layer and cured by exposure to ultraviolet light.Yttrium aluminum garnet (Y 3 Al 5 O 12 , YAG͒ materials have been widely studied for their applications to fluorescent and solid state lasers, since YAG is a hard material which is not easily damaged under conditions of high irradiation. 1-4 The Y 3 Al 5 O 12 -Ce phosphor shows a bright yellow emission under excitation with a blue radiation ͑460 nm͒, and, thus, it is potentially applicable to a white light emitting diode ͑LED͒ by combining it with a blue gallium nitride ͑GaN͒ LED. 5 To improve the luminescence efficiency, the combinatorial method and an application of BaF 2 flux were used for the phosphor synthetic process.Advantages of LEDs include high brightness, reliability, low power consumption, and a long life. 6,7 The use of a blue LED for a white light prevents the generation of ultraviolet ͑UV͒ light by a fluorescent lamp. Applications of white LEDs can be found in general lighting including illuminations, displays, and signage. 7 The uniformity, optimized thickness, and packing density of a yellow phosphor layer on a GaN chip are important for achieving a highly efficient white LED. The adhesion strength of the phosphor layer on a GaN chip is also critical, since the weak adhesion strength of the phosphor layer may result in the dislodging of the phosphor during processing or a short lifetime of the fabricated white LED. For the coating of a yellow phosphor on a GaN chip, several methods such as slurry, settling, and electrophoretic deposition ͑EPD͒ are available.The slurry method is based on coating such as flowing, dipping, spinning, and photodevelopment of a phosphor suspension in a photoresist. A photochemical reaction such as the oxidation of poly͑vinyl alcohol͒ ͑PVA͒ and the reduction of ammonium dichromate ͑ADC͒ occurs and results in cross-linki...