| 摘要 |
PURPOSE:To contrive the improvement of the linearity of the current-photo- output characteristic withot largely deteriorating the fiber coupling power, by suitably choosing the band gap energy of each semiconductor layer in an LED constituted of III-V group compound semiconductors. CONSTITUTION:On an N type InP substrate 21, an N type InP layer 22 with band gap energy Eg=Eg1, a P type InGaAsP layer 23 (Eg=Eg2<Eg1), a P type InGaAsP layer 24 (Eg=Eg3>Eg2), a P type InGaAsP layer 25 (Eg=Eg4<Eg2) and a P type InP layer 26 (Eg=Eg5>Eg4) are successively formed. When the current is passed through this LED in a forward direction, the electron-hole recombination occurs. When this current is further increased, the electron leak current exceeding the hetero barrier between the layer 24 increases. The remnant recombined in the layer 24 of electrons exceeding this barrier reaches the layer 25, recombines with holes there and emits the light of energy Eg4. Since the current injected into this layer 25 is the electron leak current, the linearity of the current-photo-output characteristic is largely improved. |
