Nitride semiconductor vertical cavity surface emitting laser

1. A vertical cavity surface emitting laser (VCSEL), comprising:

a first optical reflector;

a base region having a vertical growth part laterally adjacent the first optical reflector and a lateral growth part comprising a nitride semiconductor material vertically over at least a portion of the first optical reflector;

an active region having at least one nitride semiconductor quantum well vertically over at least a portion of the lateral growth part of the base region, the active region comprising a first dopant of a first electrical conductivity type;

a contact region comprising a nitride semiconductor material laterally adjacent the active region such that current is injected transversely into the active region and a second dopant of a second electrical conductivity type opposite the first electrical conductivity type; and

a second optical reflector vertically over the active region and forming with the first optical reflector a vertical optical cavity vertically overlapping at least a portion of the at least one quantum well of the active region.

2. The VCSEL of claim 1 , wherein the base region is formed of Al x In y Ga 1-x-y N, where 0≦x,y≦1 and 0≦x+y≦1.

3. The VCSEL of claim 2 , wherein the base region is formed of GaN.

4. The VCSEL of claim 1 , wherein the contact region is formed of AI x In y Ga 1-x-y N, where 0≦x,y≦1 and 0≦x+y≦1.

5. The VCSEL of claim 4 , wherein the contact region is formed of GaN.

6. The VCSEL of claim 1 , wherein the first dopant is an n-type dopant and the second dopant is a p-type dopant.

7. The VCSEL of claim 1 , wherein the active region comprises a quantum well layer between a pair of barrier layers, each of the quantum well and barrier layers being formed of respective nitride semiconductor material selected from Al x In y Ga 1-x-y N, where 0≦x,Y≦1 and 0≦x+y1.

8. The VCSEL of claim 7 , wherein the barrier layers are formed of GaN, and the quantum well layer is formed of InGaN.

9. The VCSEL of claim 7 , wherein the barrier layers are doped with the first dopant.

10. The VCSEL of claim 9 , wherein the quantum well layer is doped with the first dopant.

11. The VCSEL of claim 1 , further comprising a first electrode forming an ohmic contact with the contact region.

12. The VCSEL of claim 11 , further comprising a second electrode forming an ohmic contact with the active region.

13. The VCSEL of claim 11 , further comprising a second electrode electrically connected to the active region through the base region.

14. The VCSEL of claim 1 , wherein the at least one quantum well substantially coincides with a peak in a standing optical wave having a specified optical wavelength in the vertical optical cavity.

15. A vertical cavity surface emitting laser (VCSEL), comprising:

a first distributed Bragg reflector;

a GaN base region having a vertical growth part laterally adjacent the first optical reflector and a lateral growth part vertically over at least a portion of the first optical reflector;

an active region vertically over at least a portion of the lateral growth part of the base region and comprising an n-type dopant, wherein the active region comprises a quantum well layer between a pair of barrier layers, each of the quantum well and barrier layers being formed of respective nitride semiconductor material selected from Al x In y Ga 1-x-y N, where 0≦x,y≦1 and 0≦x+y≦1;

a GaN contact region laterally adjacent the active region such that current is injected transversely into the region and comprising a p-type dopant; and

a second distributed Bragg reflector vertically over the active region and defining with the first optical reflector a vertical optical cavity overlapping at least a portion of the at least one quantum well of the active region.