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Use the same contacts for GaN based UV Photodetectors

Use the same contacts for GaN based UV Photodetectors. Y.C. Chiang. Outline. Introduction Experiments Results and discussion Conclusion References. ITON Schottky contacts for GaN based UV photodetectors. N. Vanhove , J. John , A. Lorenz , K. heng,

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Use the same contacts for GaN based UV Photodetectors

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  1. Use the same contacts for GaN based UV Photodetectors Y.C. Chiang

  2. Outline • Introduction • Experiments • Results and discussion • Conclusion • References

  3. ITON Schottky contacts for GaN based UV photodetectors N. Vanhove , J. John , A. Lorenz , K. heng, G. Borghs , J.E.M. Haverkort

  4. Introduction • Due to the low transmission of UV light in the metal layers, transparent oxides like ITON should improve sensitivity of the photodetector. • In spectroscopic measurements, ITON has shown an improved UV transmission.

  5. Experiments 100 nm 20/40/25/50 nm Fig. 1. Schematic cross section of a Schottky UV photodiode.

  6. Results and discussion Fig. 2. I–V characteristic of an ITON/GaN Schottky diode (dark and under UV illumination).

  7. Results and discussion 30 A/W Fig. 3. Spectral responsivity of a typical ITON/GaN photodiode at bias of -1 V.

  8. Results and discussion Fig. 4. C–V measurement of an ITON/GaN Schottky diode under dark conditions and under UV illumination.

  9. Results and discussion Fig. 5. Transient behavior of the UV response of an ITON/GaN Schottky-Barrier diode at a bias voltage of -1 V.

  10. Conclusion • Photodetectors with excess photocurrent showed the effect of persistent photocurrent when UV light was switched off.

  11. References N. Vanhove, J. John, A. Lorenz, K. Cheng, G. Borghs, J.E.M. Haverkort, ITON Schottky contacts for GaN based UV photodetectors, Appl. Surf. Sci., 253(5), 2930-2932, (2006)

  12. Gallium nitride photoconductive ultraviolet sensor with a sputtered transparent indium-tin-oxide ohmic contact Y.C. Jiang

  13. Outline • Introduction • Experimental details • Results and discussion • Conclusions • References

  14. Introduction • The reasonably large Schottky barrier height at ITO/n-GaN interface also suggests ITO could be used as the contact electrodes of GaN-based MSM photodetectors.

  15. Experimental details Fig. 1. A designed MSM pattern with two interdigitated electrodes.

  16. Experimental details Fig. 2. The optical transmittance as a function of wavelength for ITO films.

  17. Experimental details Fig. 3. The I –V curves of the ITO/n-GaN samples with as-deposited, 500 and 600 -C annealing conditions.

  18. Results and discussion Fig. 4. The dark and illuminated I –V characteristics of as-deposited ITO MSM photoconductors on GaN.

  19. Results and discussion 327 A/W Fig. 5. Photo-responsivity of as-deposited ITO MSM photoconductor on GaN.

  20. Conclusions ITO layers were deposited onto n-GaN films by RF sputtering. The deposited ITO became more transparent after proper annealing and formed good ohmic contacts on n-GaN.

  21. References J.D. Hwang and C.C. Lin, “Gallium nitride photoconductive ultraviolet sensors with a sputtered transparent indium-tin-oxide ohmic contact”, Thin Solid Films, 491, pp.276-279, 2005.

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