JPS5735393A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To make a semiconductor laser device to generate no reactive current and to contrive to reduce the threshold current thereof by a method wherein when the necessary semiconductor layers are to be formed in order on a semiconductor substrate, a transparent N type semiconductor layer is formed between the substrate and a P type semiconductor layer to be jointed to the substrate. CONSTITUTION:A P type GaAlAs layer 102, an N type GaAl layer 103, an N type GaAs active layer 104, and an N type GaAlAs layer 105 are made to grow in order on an I type GaAs substrate 101 by the liquid phase epitaxial growth technique, etc. At this time, an N type GaAlAs layer 301 is formed between the substrate 101 and the P type layer 102, and the forbidden band gap of the N type layer 301 is made as broader than that of the active layer 104 as to become transparent to radiation of an active region 111 Therefore because excitation of a pair of electron and hole to be caused by absorption of light in a degenerated layer 112 is not generated, the Fermi level of the N type layer 301 is held at a constant, and a PN hetero junction 302 performs current blocking function. Accordingly the reactive current A is not generated, and reduction of the threshold current can be attained.