Abstract
We developed a new concept of X- and γ-ray radiation semiconductor detectors based on a large area graphene/semi-insulating single crystal CdTe Schottky-type heterojunction. These two terminal electronic devices can be easily fabricated by forming a Van der Waals contact between large area chemical vapor deposited graphene and CdTe substrates in air and at room temperature. This approach significantly reduces the fabrication cost and improves the reproducibility and stability of electrical properties. A detailed analysis of their AC and DC electrical properties was carried out in order to determine the width of the space charge region and dominant charge transport mechanisms at reverse bias. The unoptimized graphene/CdTe heterojunction detectors exhibited a promising spectral resolution of 241Am (59 keV) and 137Cs (662 keV) isotope radiation at room temperature.
Highlights
Graphene is a promising candidate for applications in the form of the front electrical contact for radiation detectors widely employed in science, engineering, medicine, and other fields
We proposed a new concept of a Schottky-type semiconductor heterojunction detectors based on a Van der Waals contact between large area chemical vapor deposition (CVD)-grown graphene and semi-insulating single crystal CdTe
The developed model was successfully employed to determine the real values of the crucial parameters relevant to Schottky diode-type semiconductor detectors: the width of the space charge region at zero bias WV=0 = 0.18 mm and the concentration of uncompensated acceptors NA−ND = 2.89 × 1010 cm−3 in the semi-insulating CdTe active material
Summary
Graphene is a promising candidate for applications in the form of the front electrical contact for radiation detectors widely employed in science, engineering, medicine, and other fields. High-resistivity CdTe single crystals suffer from significant temperature instabilities and uncontrollable time fluctuations of electrical characteristics due to polarization and compensation processes[6,7,8,9,10,11,12]. This study aims to prepare novel graphene/single crystal CdTe heterojunction radiation detectors excluding undesirable vacuum deposition processes and technological heat treatments that may induce surface defects and modify the compensation level in the bulk of the CdTe active layer. Features of their impedance spectra and DC current-voltage characteristics were analyzed in details. Their spectroscopic detecting characteristics were measured at different reverse bias and room temperature
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