Characterization of CdTe/n$^{+}$-Si Heterojunction Diodes for Nuclear Radiation Detectors

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> CdTe/n<formula formulatype="inline"><tex>$^{+}$</tex></formula>-Si heterojunction diodes were fabricated and characterized for the development of gamma ray detectors. With the careful control of the growth parameters thick single crystal CdTe epilayers of high-crystalline quality were grown directly on the (211) Si substrates in a metalorganic vapor phase epitaxy. The heterojunction diode was fabricated by growing a 5 <formula formulatype="inline"><tex>$\mu$</tex> </formula>m thick n-type CdTe buffer layer on the n<formula formulatype="inline"> <tex>$^{+}$</tex></formula>-Si substrate, followed by the growth of 100 <formula formulatype="inline"><tex>$\mu$</tex></formula>m thick undoped p-CdTe layer. The diode fabricated showed very good rectification property with a low value of the reverse bias leakage current, typically <formula formulatype="inline"> <tex>$1.26 \times 10^{- 7}$</tex></formula> A/cm<formula formulatype="inline"> <tex>$^{2}$</tex></formula> for an applied reverse bias of 60 V. The diode clearly demonstrated the gamma radiation detection capability by resolving energy peaks from the <formula formulatype="inline"><tex>$^{241}$</tex></formula>Am radioisotope during the radiation detection test performed at room temperature. </para>