Electrical Conductivity of Monocrystalline Cuprous Oxide

The electrical conductivity σ of single crystals of cuprous oxide was measured from 25° to 1100°C and at oxygen pressures PO₂ from 10^—5 to 760 mm. Except at very low PO₂ the σ at all T is due entirely to positive holes associated with native defects (cation vacancies). The different activation energies which occur in different temperature regions can be quantitatively interpreted on this basis. For example, in 1.4 mm O₂ and T above 750°C, ${\text{σ=2.3×10}}^3\hspace{0.17em}\exp {\mathrm{(-\epsilon }}_1\mathrm{/kT)}$ with ε₁=0.625 ev. This ${\epsilon }_1{\mathrm{=\epsilon }}_3\text{+(ΔH/2)}$ , where ΔH is the heat of solution of an atom of oxygen and ε₃ is the activation energy for motion of positive holes in an electric field (ε₃=0.295 ev and ΔH=0.63 ev). Polycrystalline cuprous oxide doped with beryllium displayed a conductivity consistent with an increase in vacancies and decrease in free positive holes due to incorporation of Be²⁺.