A CVD diamond-based photodetector for the visible and near-IR spectral range

A photodetector for the visible and near-IR spectral range has been created on the basis of a chemical- vapor-deposited diamond modulation-doped with boron. The detected electromagnetic radiation is absorbed in a thin Cr (7 nm)–Au (5.5 nm) bimetallic sublayer deposited on the surface of a modulationdoped diamond film comprising a highly doped (up to 5 $\times$ 10$^{19}$ cm$^{-3}$) 3-nm-thick delta-layer, low-doped ($\sim$10$^{17}$ cm$^{-3}$) 800-nm-thick sublayer, and highly doped (10$^{20}$ cm$^{-3}$) $\sim$10-$\mu$m-thick sublayer with an ohmic Ti(50 nm)/Pt(15 nm)/Au(30 nm) contact. Holes generated in the bimetallic sublayer diffuse into diamond and are accelerated by an electric field in the low-doped sublayer to form a response photocurrent. The ampere/watt responsivity of the photodetector reaches 1 $\mu$A/W at a radiation wavelength of 445 nm and 0.18 $\mu$A/W at 1.06 $\mu$m.