Thermal detection of single e-h pairs in a biased silicon crystal detector

Abstract

We demonstrate that individual electron-hole pairs are resolved in a 1 cm${}^2$ by 4 mm thick silicon crystal (0.93 g) operated at $\sim$35 mK. One side of the detector is patterned with two quasiparticle-trap-assisted electro-thermal-feedback transition edge sensor (QET) arrays held near ground potential. The other side contains a bias grid with 20\% coverage. Bias potentials up to $\pm$ 160 V were used in the work reported here. A fiber optic provides 650~nm (1.9 eV) photons that each produce an electron-hole ($e^{-}{h}^{+}$) pair in the crystal near the grid. The energy of the drifting charges is measured with a phonon sensor noise $\ddot{I}ƒ$ $\sim$0.09 $e^{-}{h}^{+}$ pair. The observed charge quantization is nearly identical for $h^{+}$'s or $e^{-}$'s transported across the crystal.

4 journal pages, 5 figures