Evidence for a hard gap and Wigner lattice in heavily boron-doped synthetic diamond

Sudo, Tomoko*; Ohashi, Kazutoshi*; Sato, Toshimaro*; Ota, Eiji*; Okayasu, Satoru  ; Sugai, Hiroyuki

We have measured low frequency generation-recombination noise (g-r moise) spectra of a heavily boro-doped diamond crystal over the temperature range 20-300 K. The experimental results show that there are two peaks in the g-r noise spectrum at 120 K and 67 K, respectively. The 120 K peak corresponds to experimental evidence for the existence of hard gap having width of 10.4 meV. We interpret the 67 K peak as evidence for Wigner lattice formation whose gap width is 5.8 meV.