Drift mobility measurements have been made on eleven silicon single crystals ranging in resistivity from 19 to 180 ohm cm. The drift mobility of electrons (${\mu }_n$) in the purest $p$-type crystals and of holes (${\mu }_p$) in the purest $n$-type crystals can be expressed by the formulas ${\mu }_n=(2.1\mathrm{}\pm 0.2)\times {10}^9{T}^{-2.5\mathrm{}\pm 0.1}$ and ${\mu }_p=(2.3\mathrm{}\pm 0.1)\times {10}^9{T}^{-2.7\mathrm{}\pm 0.1}$ between 160 and 400°K. At 300°K ${\mu }_n$ and ${\mu }_p$ are 1350±100 and 480±15 ${\mathrm{cm}}^2$ (volt ${\mathrm{s}\mathrm{e}\mathrm{c})}^{-1\mathrm{}}$, respectively. The conductivity of some of these crystals was measured between 78 and 400°K, and provides independent evidence for the temperature dependences of mobility quoted in the foregoing.

Below 100°K hole mobility in the $n$-type crystals decreases markedly, probably at least in part because of short-time trapping of the injected holes.

• Received 21 November 1955

DOI:https://doi.org/10.1103/PhysRev.101.1699