Schottky contacts to high-resistivity epitaxial GaAs layers for detectors of particles and X- or $\gamma$-ray photons

The electrical characteristics of Ti and Pt Schottky contacts to epitaxial $n$-GaAs layers with the charge-carrier concentration $<$ 10$^{12}$ cm$^{-3}$ for detectors of particles and X- or $\gamma$-ray photons are studied. It is shown that it is preferable to use a diffusion-based theory of charge transport in calculations of the parameters of Schottky contacts to thick high-resistivity lightly compensated GaAs layers. The calculated barrier heights were 0.84 and 0.87 eV for the Ti and Pt contacts, respectively. The fabricated samples of the surface-barrier detectors featured a linear response in the studied range of energies from 6 to 140 keV for $\gamma$-ray photons and from 4 to 8 MeV for $\alpha$ particles; the efficiency of charge collection was close to 100% and the energy resolution was high at room temperature.