Gallium nitride based compound semiconductor light-emitting device

A light-emitting semiconductor device including:

• a nitride based compound semiconductor multilayer structure which further includes:
• an active layer;
• a first-side cladding layer under said active layer;
• a second-side cladding layer over said active layer;
• and
• at least one of a first-side optical guide layer over said first-side cladding layer and under said active layer and a second-side optical guide layer over said active layer and under said second-side cladding layer,
• wherein the following four equations are satisfied:
• 0.15≦h;
• |x−y|≦0.02;
• 0.02≦x≦0.06;
• and
• 0.21y−0.42≦d2+h,
• where “h” (micrometers) represents a total thickness of said at least one of said first-side and second-side optical guide layers;
• “d2” (micrometers) represents a thickness of said second-side cladding layer;
• “x” represents a first Al-index of a first AlGaN bulk crystal which has a first refractive index equal to a first averaged refractive index of said first-side cladding layer;
• and “y” represents a second Al-index of a second AlGaN bulk crystal which has a second refractive index equal to a second averaged refractive index of said second-side cladding layer.

A light-emitting semiconductor device including:

• a nitride based compound semiconductor multilayer structure which further includes:
• an active layer;
• a first-side cladding layer under said active layer;
• a second-side cladding layer over said active layer;
• and
• at least one of a first-side optical guide layer over said first-side cladding layer and under said active layer and a second-side optical guide layer over said active layer and under said second-side cladding layer,
• wherein the following four equations are satisfied:
• 0.15≦h;
• y−x>0.02;
• 0.03≦x≦0.06;
• and
• 0.47x−0.5≦d1+4h,
• where “h” (micrometers) represents a total thickness of said at least one of said first-side and second-side optical guide layers;
• “d1” (micrometers) represents a thickness of said first-side cladding layer;
• “x” represents a first Al-index of a first AlGaN bulk crystal which has a first refractive index equal to a first averaged refractive index of said first-side cladding layer;
• and “y” represents a second Al-index of a second AlGaN bulk crystal which has a second refractive index equal to a second averaged refractive index of said second-side cladding layer.

A light-emitting semiconductor device including:

• a nitride based compound semiconductor multilayer structure which further includes:
• an active layer;
• a first-side cladding layer under said active layer;
• a second-side cladding layer over said active layer;
• and
• at least one of a first-side optical guide layer over said first-side cladding layer and under said active layer and a second-side optical guide layer over said active layer and under said second-side cladding layer,
• wherein the following four equations are satisfied:
• 0.15≦h;
• y−x>0.02;
• 0.03≦x≦0.06;
• and
• 0.2y−0.33≦d2+0.5h,
• where “h” (micrometers) represents a total thickness of said at least one of said first-side and second-side optical guide layers;
• “d2” (micrometers) represents a thickness of said second-side cladding layer;
• “x” represents a first Al-index of a first AlGaN bulk crystal which has a first refractive index equal to a first averaged refractive index of said first-side cladding layer;
• and “y” represents a second Al-index of a second AlGaN bulk crystal which has a second refractive index equal to a second averaged refractive index of said second-side cladding layer.

A light-emitting semiconductor device including:

• a gallium nitride based compound semiconductor base layer;
• and
• a nitride based compound semiconductor multilayer structure over said gallium nitride based compound semiconductor base layer, and said nitride based compound semiconductor multilayer structure further including:
• an active layer;
• a first-side cladding layer under said active layer;
• a second-side cladding layer over said active layer;
• and
• at least one of a first-side optical guide layer over said first-side cladding layer and under said active layer and a second-side optical guide layer over said active layer and under said second-side cladding layer,
• wherein a vertical radiation angle of a laser beam emitted from said light-emitting semiconductor device is not more than 20 degrees, and further the following equation is satisfied:
• n s 2 ⁢ - ⁢ n e 2 n e · ⁢ 4 ⁢ ⁢ ( n e 2 ⁢ - ⁢ n c 2 ) n s 2 ⁢ - ⁢ n c 2 · [ [LeftBracketingBar] f ⁡ ( z 0 ) [RightBracketingBar] 2 / ⁢ ∫ - ∞ + ∞ ⁢ f * ( ⁢ z ) ⁢ ⁢ f ⁡ ( z ) ⁢ ⁢ ⅆ z ] ⁢ ≤ 2 ⁢ ⁢ c ⁢ ⁢ m - 1 ( 7 )
• where “ns” represents a refractive index of said gallium nitride based compound semiconductor base layer;
• “nc” represents an averaged refractive index of said first-side cladding layer;
• “ne” represents a waveguide mode equivalent refractive index;
• “z” represents a coordinate axis along a direction vertical to interfaces of said nitride based compound semiconductor multilayer structure, provided a positive direction of said coordinate axis is toward said gallium nitride based compound semiconductor base layer, “f(z)” represents a function in z-coordinate system of a field distribution of laser beam, and “z0” represents a position projected on said z-coordinate axis of a first interface of said first-side cladding layer, provided said first interface is closer to said gallium nitride based compound semiconductor base layer.

A light-emitting semiconductor device including:

• a gallium nitride based compound semiconductor substrate;
• a nitride based compound semiconductor multilayer structure over said gallium nitride based compound semiconductor substrate, and said nitride based compound semiconductor multilayer structure further including:
• an active layer;
• a first-side cladding layer under said active layer;
• a second-side cladding layer over said active layer;
• and
• at least one of a first-side optical guide layer over said first-side cladding layer and under said active layer and a second-side optical guide layer over said active layer and under said second-side cladding layer;
• and
• a second-side electrode closer to said second-side cladding layer than said active layer,
• wherein a vertical radiation angle of a laser beam emitted from said light-emitting semiconductor device is not more than 20 degrees, and further the following equation is satisfied:
• 3·αmetal·Γp≦5 cm−1 (8)
• where “αmetal” represents an optical absorption coefficient of said second-side electrode, and “Γp” represents a waveguide mode optical confinement coefficient of said second-side electrode.