JPS5574196A - Semiconductor laser - Google Patents

Abstract

PURPOSE: To reduce a threshold value of a current by concentrating a current into a portion of an active layer by untilizing the spread resistance of the active layer.

CONSTITUTION: On a p-type crystal substrate 1, an n-type layer 2 wherein the width of a forbidden band which is to become a clad layer is E₁ and the refractive index is n₁, a p-type layer 3 wherein the width of a forbidden band which is to become an active layer is E₂ and the refractive index is n₂, and an n-type layer 4 wherein the width of a forbidden band which is to become a clad layer is E₃ and the refractive index is n₃ are epitaxially grown sequentially. In this case, n₂>n₁, n₃; E₂<E₁, E₃. p-Type impurities Zn are diffused from the surface of a wafer obtained in this way until the substrate 1 is reached, and a p-type region 5 is formed. Furthermore, an electrode 6 is attached to the non-diffused region of the layer 4, and an electrode 7 is attached to the substrate 1. A resonator mirror is provided on a plane perpendicular to the long and narrow diffused region. When a positive potential is applied to a lead wire 9 and a negative potential is applied to a lead wire 8, the junction plane between the layers 2 and 3 becomes a current-stopping barrier. In this constitution, electrons in the layer 4 flow through an injection route of a current flow 10, and injected to the layer 3 only at its end portion which contacts with the region 5, therely the current is concentrated and the threshold value is reduced.

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