1. High responsivity 4H-SiC Schottky UV photodiodes based on the pinch-off surface effect
Antonella Sciuto, Fabrizio Roccaforte, Salvatore Di Franco, and Vito Raineri

2. Outline INTRODUCTION EXPERIMENTAL SETUP RESULTS AND DISCUSSION
CONCLUSION
REFERENCES

3. INTRODUCTION
Some works in the last decade reported p-i-n UV detectors on SiC with promising UV performances and ultraviolet-visible rejection ratio of about 1002.
Schottky diodes are majority carrier devices, thus allowing a faster response than p-n junctions.

4. EXPERIMENTAL SETUP M M M S S M
水平式
垂直式

5. 示意圖
水平式的電極圖形
垂直式的電極圖形

7. Optical microscopy image of one of the fabricated devices, showing the interdigit front electrode with 11.4 m spaced metal stripes.

8. RESULTS AND DISCUSSION
Photocurrent of vertical 4H-SiC interdigit Schottky photodiode with 5.4 m spaced metal stripes as a function of the reverse bias, under dark conditions and under illumination at 256 nm.

9. Internal responsivity vs wavelength of the vertical 4H-SiC Schottky UV detectors at a 20 V reverse bias. Close to the experimental data points,the calculated internal QE is also reported. In the investigated wavelength range, the maximum in the R, 160 mA/W, and in the internal QE, 78%, is reached at 256 nm.

10. Comparison of the photocurrent of vertical 4H-SiC Schottky UV detectors and planar MSM detectors with 11.4 m spaced metal stripes,under dark conditions and under illumination at 256 nm. The response of the vertical detector is a factor of 1.4 higher than that of the planar MSM structure.

11. CONCLUSION
high responsivity 4H-SiC vertical photodiodes were demonstrated exploiting the surface pinch-off effect.
The vertical photodiodes showed an ultraviolet-visible rejection ratio >7×103 and a responsivity a factor of about 1.8 higher than a conventional planar metal-semiconductor-metal structure.

12. REFERENCES
High responsivity 4H-SiC Schottky UV photodiodes based on the pinch-off surface effect
Comprehensive characterization of metal–semiconductor–metal ultraviolet photodetectors fabricated on single-crystal GaN
Richardson’s constant in inhomogeneous silicon carbide Schottky contacts