Nitride semiconductor light emitting device and method of manufacturing the same

Abstract

The present invention provides a nitride semiconductor light emitting device having an n-electrode that has an Au face excellent in ohmic contacts to an n-type nitride semiconductor and excellent in mounting properties, and a method of manufacturing the same. The nitride semiconductor light emitting device uses an n-electrode having a three-layer laminate structure that is composed of a first layer containing aluminum nitride and having a thickness not less than 1 nm or less than 5 nm, a second layer containing one or more metals selected from Ti, Zr, Hf, Mo, and Pt, and a third layer made of Au, from the near side of the n-type nitride semiconductor in order of mention. The n-electrode thus formed is then annealed to obtain ohmic contacts to the n-type nitride semiconductor.

1 . A nitride semiconductor light emitting device, comprising:
 an n-type nitride semiconductor layer provided over a substrate;   a light emitting layer provided over the n-type nitride semiconductor layer, for emitting light of a predetermined wavelength;   a p-type nitride semiconductor layer provided over the light emitting layer;   an n-electrode electrically connected to the n-type nitride semiconductor layer; and   a p-electrode electrically connected to the p-type nitride semiconductor layer,   wherein the n-electrode has a laminate structure composed of a first layer, a second layer, and a third layer, from the near side of the n-type conductive substrate in order of mention,   the first layer contains aluminum nitride and has a thickness not less than 1 nm or less than 5 nm,   the second layer contains one or more metals selected from Ti, Zr, Hf, Mo, and Pt, and   the third layer is made of Au.   
     
     
         2 . The nitride semiconductor light emitting device according to  claim 1 , wherein an electrical property making a junction between the n-electrode and the n-type conductive substrate is an ohmic property. 
     
     
         3 . The nitride semiconductor light emitting device according to  claim 1 , wherein the second layer of the n-electrode has a two-layer structure having Ti provided at the near side of the n-type conductive substrate and Pt provided at the far side. 
     
     
         4 . The nitride semiconductor light emitting device according to  claim 1 , wherein the aluminum nitride is provided in form of islands, so as to expose at least part of the surface of the n-type conductive substrate. 
     
     
         5 . The nitride semiconductor light emitting device according to  claim 1 , wherein the substrate includes an n-type conductive nitride semiconductor, and
 the n-electrode is provided onto the surface near the n-type nitride semiconductor layer of the n-type conductive substrate, or onto the rear side opposite to the surface.   
     
     
         6 . The nitride semiconductor light emitting device according to  claim 1 , wherein the n-type conductive substrate is provided over an insulation material, and
 the n-electrode is provided onto the surface near the n-type nitride semiconductor layer of the n-type conductive substrate.   
     
     
         7 . The nitride semiconductor light emitting device according to  claim 1 , wherein the nitride semiconductor light emitting device is a light emitting diode (LED). 
     
     
         8 . The nitride semiconductor light emitting device according to  claim 1 , wherein the nitride semiconductor light emitting device is a laser diode (LD). 
     
     
         9 . A method of manufacturing a nitride semiconductor light emitting device, the method including the steps of:
 forming, over a substrate, an n-type nitride semiconductor layer containing at least an n-type impurity;   forming, over the n-type nitride semiconductor layer, a light emitting layer for emitting light of a predetermined wavelength;   forming, over the light emitting layer, a p-type nitride semiconductor layer containing a p-type impurity;   forming, in contact with the p-type nitride semiconductor layer, a p-electrode;   laminating, over one surface of the n-type conductive substrate and from the near side of the substrate in order of mention, a first layer containing aluminum nitride and having a thickness not less than 1 nm or less than 5 nm, a second layer containing one or more metals selected from Ti, Zr, Hf, Mo, and Pt, and a third layer made of Au; and   after the lamination process, carrying out an annealing process on the substrate.   
     
     
         10 . The method of manufacturing a nitride semiconductor light emitting device according to  claim 9 , wherein the annealing is carried out at a temperature range of 400° C. to 600° C. 
     
     
         11 . The method of manufacturing a nitride semiconductor light emitting device according to  claim 9 , wherein the aluminum nitride is formed by sputtering.