| 摘要 |
An n-type clad layer, a light-emitting layer, a p-type clad layer of gallium-nitride-group compound semiconductor are stacked on a substrate in the order. The composition distribution of gallium-nitride-group compound semiconductor forming the p-type clad layer is varied in the direction of layer thickness at a substantially continuous change rate, or it is varied in change rate of the stepping mode, so as the forbidden band width gradually decreases along with an increasing distance from the light-emitting layer. With the above-described structure, the operating voltage is lowered, while the luminous efficiency is improved.
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