Disclosed is an AlGaInN LED with improved external quantum efficiency, in which a chip employing the LED has a horizontal plane formed in a lozenge shape so that the amount of total reflection of light is reduced when the light generated from an active layer interposed between hetero-semiconductor layers with different band gaps is emitted to the outside. Since the horizontal plane of the LED is formed to have a lozenge shape so that the amount of total reflection of light generated in the LED is reduced, it is possible to maximize external quantum efficiency determined by the degree of emission of the light generated in the active layer. The cleaved plane of the LED coincides with the crystal orientation of a wafer made of GaN or sapphire, thus improving the yield of the LED when the LED is cut and produced. Since an anode and a cathode of the LED are disposed so that they diagonally face each other, it is possible to optimize the current spreading between the anode and the cathode and to improve luminous efficiency so that light generated in the active layer is uniformly emitted.