Nonparabolic Conduction Band in HgSe and HgSe0.5Te0.5

Abstract

The dependence of electron effective mass ($m^{*}$) on carrier concentration ($N$) has been determined for samples of $n$-type HgSe ($N=5\mathrm{}\times {10}^{17} \mathrm{to} 3\times {10}^{19}$ ${\mathrm{cm}}^{-3\mathrm{}}$) and Hg${\mathrm{Se}}_{0.5}$ ${\mathrm{Te}}_{0.5}$ alloy ($N=9\mathrm{}\times {10}^{17} \mathrm{to} 9\times {10}^{18}$ ${\mathrm{cm}}^{-3\mathrm{}}$) by means of infrared reflectivity and magnetoreflectivity measurements. In both cases, $m^{*}$ increases markedly with $N$. For HgSe, the variation of $m^{*}$ with $N$ is quantitatiely consistent with the conduction band model derived by Kane for InSb. The band parameters derived from the data are $P=8\mathrm{}\times {10}^{-8\mathrm{}}$ ev-cm, in close agreement with the values determined for InSb and other III-V compounds, and ${\epsilon }_g\sim 0.2$ ev. The data for Hg${\mathrm{Se}}_{0.5}$ ${\mathrm{Te}}_{0.5}$ appear to be qualitatively consistent with Kane's model, although they exhibit too much scatter for quantitative comparison.