Light-emitting semiconductor device using group III nitride compound

Abstract

A Group III nitride compound semiconductor includes a multiple layer structure having an emission layer between an n-type cladding layer and a p-type cladding layer. The n-type cladding layer may be below the emission layer, having been formed on another n-type layer which was formed over a buffer layer and a sapphire substrate. The emission layer has a thickness which is wider than the diffusion length of holes within the emission layer. The n-type cladding layer is doped with a donor impurity and has a lattice constant substantially equal to a lattice constant of the emission layer. The p-type cladding layer is doped with an acceptor impurity and has a forbidden band sufficiently wider than the forbidden band of the emission layer in order to confine electrons injected into the emission layer.

What is claimed is:  
     
         1 . A Group III nitride compound semiconductor comprising: 
 a triple layer structure having an emission layer sandwiched between an n-type cladding layer and a p-type cladding layer;    said emission layer satisfying the formula Al x1 Ga y1 In 1-x1-y1 N, where 0≦x 1 ≦1, 0≦y 1 ≦1, and 0≦x 1 +y 1 ≦1, and having a thickness larger then diffusion length of holes;    said n-type cladding layer satisfying the formula Al x2 Ga y2 In 1-x2-y2 N, where 0≦x 2 ≦1, 0≦y 2 ≦1and 0≦x 2 +y 2 ≦1, being doped with a donor impurity, and having a lattice constant substantially equal to a lattice constant of said emission layer: and    said p-type cladding layer satisfying the formula Al x3 Ga y3 In 1-x3-y3 N, where 0≦x 3 ≦1, 0≦y 3 ≦1, and 0≦x 3 +y 3 ≦1, being doped with an acceptor impurity, having a forbidden band sufficiently wider than a forbidden band of said emission layer to confine electrons injected into said emission layer.    
     
     
         2 . The Group III nitride compound semiconductor according to  claim 1 , wherein said emission layer comprises Ga y2 In 1-y2 N, ,where 0.92≦y 2 ≦1, and wherein said n-type cladding layer comprises gallium nitride (GaN) doped with a donor impurity.  
     
     
         3 . The Group III nitride compound semiconductor according to  claim 2 , wherein said n-type cladding layer is formed on a lower n type layer comprising gallium nitride (GaN), said lower n-type layer being doped with a donor impurity and comprising a donor impurity density higher than a donor impurity density of said n-type cladding layer.  
     
     
         4 . The Group III nitride compound semiconductor according to  claim 1 , wherein said donor impurity is silicon (Si).  
     
     
         5 . The Group III nitride compound semiconductor according to  claim 1 , wherein said acceptor impurity is magnesium (Mg).  
     
     
         6 . The Group III nitride compound semiconductor according to  claim 1 , wherein said emission layer is doped with silicon (Si).  
     
     
         7 . The Group III nitride compound semiconductor comprising: 
 a multiple layer structure including an emission layer sandwiched between an n-type layer and a p-type layer:    said emission layer comprising a semiconductor material satisfying the formula Al x1 Ga y1 In 1-x1-y1 N, where 0≦x 1 ≦1, 0≦y 1 ≦1, and 0≦x 1 +y 1 ≦1, said emission layer having a thickness significantly larger than a diffusion length of holes within said emission layer:    said n-type cladding layer satisfying the formula Al x2 Ga y2 In 1-x2-y2 N, where 0≦x 2 ≦1, 0≦y 2 ≦1and 0≦x 2 +y 2 ≦1, being doped with a donor impurity; and    said p-type layer satisfying the formula Al x3 Ga y3 In 1-x3-y3 N, where 0≦x 3 ≦1, 0≦y 3 ≦1, and 0≦x 3 +y 3 ≦1, being doped with an acceptor impurity.    
     
     
         8 . The Group III nitride compound semiconductor according to  claim 7 , wherein said n-type layer has a lattice constant substantially equal to a lattice constant of said emission layer.  
     
     
         9 . The Group III nitride compound semiconductor according to  claim 8 , wherein said p-type layer comprises a forbidden band sufficiently wider than a forbidden band of said emission layer to confine electrons injected into said emission layer.  
     
     
         10 . The Group III nitride compound semiconductor according to  claim 1 , wherein misfit ratio between said lattice constant of said n-type cladding layer and said lattice constant of said emission layer is within 1%.  
     
     
         11 . The Group III nitride compound semiconductor according to  claim 8 , wherein misfit ratio between said lattice constant of said n-type cladding layer and said lattice constant of said emission layer is within 1%.  
     
     
         12 . The Group III nitride compound semiconductor according to  claim 1 , wherein said emission layer has a thickness of 0.1 μm to 1.0 μm.  
     
     
         13 . The Group III nitride compound semiconductor according to  claim 7 , wherein said emission layer has a thickness of 0.1 μm to 1.0 μm.