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SiC photodiode

Simulation quantum efficiency of p-n junction 6H-SiC photodiode

Response of SiC photodiode was analytically simulated with diffusion transport equations for abrupt doping profiles, accounting for optical interference at the device surfaces.

cross section of SiC photodiode ◄ Structure of the UV photodiode (without passivation layers).

quantum efficiency of SiC photodiode ◄ Fit of the quantum efficiency model to the experimental data obtained by Brown et al. (1993, IEEE Tans. Electron. Devices 40, 325).

Device parameters: Nd=5E18 cm-3, Na=3E17 cm-3, a top oxide thickness of 66 nm, a diffusion length of electrons of 1.76 microns, a surface recombination velocity of 1.8E6 cm/s. Shown original fit of Brown et al. did not account for charge space region at the p-n junction. Our fit with optical data of Choyke and Palik (1985, in Handbook of optical constants of solids, p.587. Orlando: Academic, Ed. E. D. Palik) is better than one with optical data of Zollner et al. (1999, J. Appl. Phys., 85, 8353).

Components of quantum efficiency spectrum of SiC photodiode ◄ Components of quantum efficiency spectrum from above fit: contributions of the bottom, depleted and top layers, total internal efficiency (without losses from aperture, reflection at the surfaces and transmission without absorption), external efficiency and limit of external efficiency (for the case without losses due to charge carrier recombination).

Effect of SiO2 top passivation layer on quantum efficiency of SiC photodiode ◄ Effect of SiO2 top passivation layer on the quantum efficiency, which is shown as energy averaged in the wavelength range 200-400 nm.

Parameters of the device are those above except the oxide thickness. Optical modeling is based on the Lambert-Beer's absorption formula and thin film stack treatment with usage the Fresnel's coefficients.

UV optical data for 6H-SiC

For the modeling 6H-SiC optical data from several sources were analysed.

Absorption anisotropy of 6H-SiC photodiode ◄ Anisotropy of optical properties of 6H-SiC as it appears in absorption coefficient.

Data of Choyke and Palik are compiled from different sources. Absorption derived from Lindquist's et al. data (2001, Appl. Phys. Lett. 78, 2715) is shown for components of 6H-SiC dielectric function parallel (blue symbols) and perpendicular (pink symbols) to the hexagonal lattice axis.

6H-SiC complex refractive coefficient ◄ Complex refractive coefficient from Choyke and Palik (text file here), and Zollner et al. data.