Technical Report

Fig. 11. The samples after 3rd and 4th photolithography processes .

8. Conclusion and future work

In this work the simulation and design of the 4H-SiC single photon avalanche diodes (SPAD) for radiation detection in NUV and MUV scale of the spectrum were performed. Ab initio absorption and impact ionization mechanisms in 4H-SiC were studied. LabVIEW code for Poisson equation solving was developed. Two unique construction solutions: vertical and planar SPAD structures with breakdown voltage of 122 and 65 volt respectively were designed and simulated. The characteristics of given two structures, namely electrical field and potential in depletion region, impact ionization coefficients, multiplication coefficient, total current and quantum efficiency were calculated. CVD epilayers for these samples were fabricated and the mask set for bevel termination and contact pads formation was developed.

In the future work we consider to fabricate bevelled structures for further analysis such as IV, CV, frequency, temperature, noise measurements, SEM investigation of structures. Apart from that, it is intended to simulate some of them. It is also considered to investigate an opportunities of heterojunction SPAD design.

9.References

[1]F. Zappa, "Avalanche photodiodes and quenching circuits for single-photon detection". Applied Optics 35 (12): (1956–1976).

[2]Jun Xu “4H-SiC detectors for low levels ultraviolet detection” (2008).

[3]S. G. Sridhara, R. P. Devaty, and W. J. Choyke, “Absorption coefficient of 4H silicon carbide from 3900 to 3250 Å”. Journal of Applied Physics 84, 2963 (1998).

[4]A. Galeckas, P. Grivickas, V. Grivickas, V. Bikbajevas and J. Linnros, “Temperature

Dependence of the Absorption Coefficient in 4Hand 6H-Silicon Carbide at 355 nm Laser

[6]L. V. Keldysh, "Concerning the theory of impact ionization in semiconductors," Sov. Phys. JETP, vol. 21, pp. 1135-1144, (1965).

[7]Wolff P. A., Phys. Rev. 95, (1954).

[8]S. M. Sze, "Physics of semiconductor devices," vol.3, pp. 674-676, (2006)

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