In this work, wafer‐scale 4H‐ and 6H‐SiC lateral and vertical Schottky UV photodetectors (PDs) and arrays were fabricated, characterized and compared. The lateral type device was configured as a metal‐semiconductor‐metal (MSM) photodetector with different finger electrode widths and spacing between the fingers. The vertical type devices were formed utilizing the MSM electrodes as a top contact and a Ni contact on the wafer backside. Both types of device were fabricated on the same wafer, as seen in the abstract figure, where the transparent part of the wafer contains lateral devices and the opaque part contains vertical devices. This enables a direct comparison of the performance of the different devices types. The best fabricated PDs exhibited a UV to dark current ratio of about five orders of magnitude. The dark current was measured to be about 100 fA (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
This paper reports on fabrication and modeling of 4H- and 6H-SiC metal-semiconductor-metal (MSM) photodetectors (PDs). MSM PDs have been fabricated on 4H-SiC and 6H-SiC epitaxial layers, and their performance analyzed by MEDICI simulation and measurements. The simulations were also used to optimize the sensitivity by varying the width and spacing of the interdigitated electrodes. The fabricated PDs with 2 µm wide metal electrodes and 3 µm spacing between the electrodes exhibited, under UV illumination, a peak current to dark current ratio of 105 and 104 in 4H-SiC and 6H-SiC, respectively. The measured spectral responsivity of 6H-SiC PDs was higher compared to that of 4H-SiC PDs, with a cutoff at 407 nm compared to 384 nm in 4H-SiC PDs. Also the peak responsivity occurred at a shorter wavelength in 6H material. A high rejection ratio between the photocurrent and dark current was found in both cases. These experimental results were in agreement with simulation.
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