24:T4dd,Room temperature nuclear radiation detectors with energy discrimination capability developed by growing thick cadmium telluride (CdTe) epitaxial layers directly on n ⁺ -Si substrates in a metal-organic vapor phase epitaxy system is reported for the first time. The CdTe/n ⁺ -Si heterojunction diode detector exhibited good rectification and charge collection properties. The reverse leakage currents were typically 1times10 ^-7 to 5times10 ^-7 A/cm ² at 50-V bias. The detector clearly demonstrated its energy discrimination capability by resolving gamma peak from the ²⁴¹ Am radioisotope during radiation detection test at room temperature25:T552, CdTe/n$^{+}$-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 $\mu$ m thick n-type CdTe buffer layer on the n $^{+}$-Si substrate, followed by the growth of 100 $\mu$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 $1.26 \times 10^{- 7}$ A/cm $^{2}$ for an applied reverse bias of 60 V. The diode clearly demonstrated the gamma radiation detection capability by resolving energy peaks from the $^{241}$Am radioisotope during the radiation detection test performed at room temperature.

Manaka OMURA

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