Laser diode device and method of manufacturing laser diode device

Abstract

A laser diode device includes: a semiconductor substrate including a semi-polar surface, the semiconductor substrate being formed of a hexagonal III-nitride semiconductor; an epitaxial layer including a light emitting layer, the epitaxial layer being formed on the semi-polar surface of the semiconductor substrate, and the epitaxial layer including a ridge section; a first electrode formed on a top surface of the ridge section; an insulating layer covering the epitaxial layer in an adjacent region of the ridge section and a side surface of the ridge section, the insulating layer covering part or all of side surfaces of the first electrode continuously from the epitaxial layer; a pad electrode formed to cover a top surface of the first electrode and the insulating layer, the pad electrode being electrically connected to the first electrode; and a second electrode formed on a surface, of the semiconductor substrate, opposite to the semi-polar surface.

The invention is claimed as follows: 
     
         1 . A method of manufacturing a laser diode device, the method comprising:
 preparing a semiconductor substrate including a semi-polar surface, the semiconductor substrate being formed of a hexagonal III-nitride semiconductor;   forming an epitaxial layer on the semi-polar surface of the semiconductor substrate, the epitaxial layer including a light emitting layer of the laser diode device;   etching the epitaxial layer to a predetermined depth thereof through a mask, and forming a ridge section in a shape of a stripe;   forming a first electrode in a region corresponding to the ridge section before the forming of the ridge section, or forming the first electrode on a top surface of the ridge section after the forming of the ridge section;   forming an insulating material layer on a surface of the epitaxial layer including a top surface of the first electrode;   etching the insulating material layer, and thereby forming an insulating layer, the insulating layer covering the epitaxial layer in an adjacent region of the ridge section and a side surface of the ridge section, and the insulating layer covering part or all of side surfaces of the first electrode continuously from the epitaxial layer;   forming a pad electrode, the pad electrode covering a top surface of the first electrode and the insulating layer, the pad electrode being electrically connected to the first electrode; and   forming a second electrode on a surface, of the semiconductor substrate, opposite to the semi-polar surface.   
     
     
         2 . The method of manufacturing a laser diode device according to  claim 1 , wherein
 the first electrode is formed before the forming of the ridge section, and   the ridge section is formed by etching with use of the first electrode as the mask.   
     
     
         3 . The method of manufacturing a laser diode device according to  claim 2 , wherein
 the etching of the insulating material layer is performed by using a resist film including an opening section as a mask, the opening section having a size with which the insulating material layer formed on the top surface of the first electrode is exposed and the insulating material layer formed on a top surface of the adjacent region of the ridge section is not exposed.   
     
     
         4 . The method of manufacturing a laser diode device according to  claim 3 , wherein
 the etching of the insulating material layer is stopped after the top surface of the first electrode is exposed and before the epitaxial layer is exposed.   
     
     
         5 . The method of manufacturing a laser diode device according to  claim 4 , wherein the insulating layer is formed of an insulating material including one or more of SiO 2 , SiN, Al 2 O 3 , and ZrO 2 .