Description:
<jats:title>Abstract</jats:title>
<jats:p>Advancement in the growth of 4H-SiC with low micropipe
densities (∼ 0.11 cm<jats:sup>-2</jats:sup>) in achieving high pure epitaxial
layers, enabled the development of high-resolution 4H-SiC alpha
particle Schottky radiation detectors for harsh environments. In
particular, the study considers two types of 4H-SiC radiation
detectors having Ni and Ti as Schottky contacts. They are fabricated
by depositing Ni and Ti on 25 μm thick n-type 4H-SiC by
epitaxially growing on 350 μm thick conducting SiC
substrates. Electrical characterization and alpha spectral
measurements performed on Ni/4H-SiC and Ti/4H-SiC SBDs are reported
in this work. The spectral measurements were carried out using
<jats:sup>241</jats:sup>Am alpha emitting radioactive source. Ni/ 4H-SiC Schottky
detector showed a better spectral response with 22.87 keV FWHM
(∼ 0.416%) at a reverse bias of 150 V for 5.48 MeV alpha
particles while Ti/4H-SiC Schottky detector achieved a resolution of
38.25 keV FWHM (∼ 0.697%) at 170 V reverse bias. This work
presented spectral broadening analysis to understand the various
factors affecting the energy resolution of the detectors. The
extracted charge collection efficiencies (<jats:italic>CCE</jats:italic>s) are
approximately 99% in both the detectors. In addition, polarization
effects are not noticed in any of the fabricated detectors. The
diffusion length of minority carriers (<jats:italic>L<jats:sup>p</jats:sup>
</jats:italic>) is computed based on
the drift-diffusion model by fitting the <jats:italic>CCE</jats:italic> curve as a
function of applied bias, and the values are close to 9 μm
and 7 μm for Ni/4H-SiC SBD and Ti/4H-SiC SBD detectors,
respectively. Annealing at 400°C for 5 minutes in N<jats:sub>2</jats:sub>
ambient resulted in resolution of 23.98 keV FWHM (∼ 0.436%)
for Ni/4H-SiC SBD detector at -170 V and 36.21 keV FWHM (∼
0.661%) for Ti/4H-SiC SBD detector at -150 V. Overall Ni/4H-SiC
SBD detectors showed superior spectral characteristics and superior
resolution when compared to Ti/4H-SiC SBD detectors. However, the
Ti/4H-SiC SBD detector fabricated in this work performed better than
the previously reported work on a similar device structure. Hence,
future work aimed at improving resolution of radiation detectors
could also consider Ti/4H-SiC SBDs along with Ni/4H-SiC SBDs.</jats:p>