Method and apparatus for downhole spectroscopy

1. An apparatus for estimating a property of a downhole fluid comprising:

a carrier that is conveyed in a borehole; and

a semiconductor electromagnetic energy source carried by the carrier, the semiconductor electromagnetic energy source having an active region that includes one or more nitride-based barrier layers that are modulation-doped using a nitride-based doped layer.

2. An apparatus according to claim 1 , wherein the carrier includes a wireline, a drill string, a slick line, a drilling sub, a BHA, or a combination thereof.

3. An apparatus according to claim 1 , wherein the semiconductor electromagnetic energy source comprises a UV electromagnetic energy emitter, a violet electromagnetic energy emitter or a combination thereof.

4. An apparatus according to claim 1 , wherein the electromagnetic energy source includes a UV laser, a violet laser or a combination thereof.

5. An apparatus according to claim 1 , wherein the one or more nitride-based barrier layers include at least one InGaN layer.

6. An apparatus according to claim 1 , wherein the nitride-based doped layer comprises a p-doped layer.

7. An apparatus according to claim 6 , wherein the p-doped layer includes AlGaN.

8. An apparatus according to claim 1 , wherein the nitride-based doped layer comprises p-blocking layer that is disposed between two barrier layers.

9. An apparatus according to claim 1 further comprising a detector responsive to an interaction between the emitted electromagnetic energy and the downhole fluid, wherein the downhole fluid property is estimated at least in part using an output signal from the detector.

10. An apparatus according to claim 9 , wherein the detector comprises a SiC photodetector.

11. An apparatus according to claim 9 , wherein the output signal is indicative of a downhole fluorescence property.

12. An apparatus according to claim 1 , wherein the semiconductor electromagnetic energy source emits monochromatic electromagnetic energy.

13. An apparatus according to claim 1 , wherein the semiconductor electromagnetic energy source includes one or more quantum wells.

14. An apparatus according to claim 1 , wherein the semiconductor electromagnetic energy source includes one or more of quantum wires, quantum dots and quantum dashes.

15. A method for estimating a property of a downhole fluid comprising:

conveying a carrier in a borehole;

carrying a semiconductor electromagnetic energy source in a borehole using the carrier, the semiconductor electromagnetic energy source having an active region that includes one or more nitride-based barrier layers that are modulation-doped using a nitride-based doped layer;

emitting electromagnetic energy from the emitter toward the downhole fluid in-situ;

detecting an interaction between the emitted electromagnetic energy and the downhole fluid using a detector; and

estimating the downhole fluid property at least in part using an output signal from the detector.

16. A method according to claim 15 , wherein emitting electromagnetic energy includes emitting monochromatic electromagnetic energy, narrow band electromagnetic energy, wide band electromagnetic energy or a combination thereof.

17. A method according to claim 15 , wherein emitting electromagnetic energy includes emitting electromagnetic energy within a UV range, within a violet range or within a range including UV and violet wavelengths.

18. A method according to claim 15 , wherein detecting an interaction between the emitted electromagnetic energy and the downhole fluid using a detector includes using a detector that includes a semiconductor SiC photodetector.

19. A method according to claim 15 , wherein detecting an interaction between the emitted electromagnetic energy and the downhole fluid includes detecting a fluorescence property of the downhole fluid.