A light-emitting semiconductor device (10) consecutively includes a sapphire substrate (1), an AlN buffer layer (2), a silicon (Si) doped GaN n⁺-layer (3) of high carrier (n-type) concentration, a Si-doped (Al_x3Ga_1-x3)_y3In_1-y3N n⁺-layer (4) of high carrier (n-type) concentration, a zinc (Zn) and Si-doped (Al_x2Ga_1-x2)_y2In_1-y2N emission layer (5), and a Mg-doped (Al_x1Ga_1-x1)_y1In_1-y1N p-layer (6). The AlN layer (2) has a 500 thickness. The GaN n⁺-layer (3) has about a 2.0 m thickness and a 210¹⁸/cm³ electron concentration. The n⁺-layer (4) has about a 2.0 m thickness and a 210¹⁸/cm³ electron concentration. The emission layer (5) has about a 0.5 m thickness. The p-layer 6 has about a 1.0 m thickness and a 210¹⁷/cm³ hole concentration. Nickel electrodes (7, 8) are connected to the p-layer (6) and n⁺-layer (4), respectively. A groove (9) electrically insulates the electrodes (7, 8). The composition ratio of Al, Ga, and In in each of the layers (4, 5, 6) is selected to meet the lattice constant of GaN in the n⁺-layer (3). The LED (10) is designed to improve luminous intensity and to obtain purer blue color.