| 摘要 |
PURPOSE:To produce LED made of InGaAsP with high efficiency and output by a method wherein an active layer with narrow forbiden band width is held by P- and N-layers successively changing the concentration of the active layer in the direction of layer thickness. CONSTITUTION:In a LED where N type In1-xGaxAs1-y active layer 32 is held by P-InP layer 33 and N-InP layer 31, the donor density of the active layer 32 is successively changed in the direction of layer thickness. When LED is supplied with forward bias voltage, if an active layer 12 is doped to increase donor density from a layer 11 to another layer 13 in a energy band diagram, the lower end of conduction band of active layer and the upper end of valency electron band are lowered in the direction of layer thickness generating an accelerating electric field for the electrons and hole injected into the active layer. Consequently the thickness of active layer almost equivalent to the conventional hole diffusion length may be increased producing LED made of InGaAsP with high efficiency and output as well as inconspicuous saturation characteristic. |
