Photoconductivity study of free-carrier, phonon-assisted, and impurity transitions in InSb at magnetic fields up to 20 T

Intraband photoconductivity of high-purity $n$- and $p$-type InSb ($n_{e,h}\approx {10}^{13}$ ${\mathrm{cm}}^{-3\mathrm{}}$) induced by C${\mathrm{O}}_2$ laser radiation has been investigated in magnetic fields up to 20 T, exhibiting a number of sharp resonances. These are shown to be associated with free-electron and LO-phonon-assisted spin-conserving and spin-flip transitions as well as impurity excitations. Phonon-assisted hole transitions have been also observed. The selection rules for intraband and interband excitations, calculated for $\overrightarrow{\mathrm{H}}\parallel \mathrm{}\left[100\right]\mathrm{}$ direction and including $k_z$ terms, warping, and inversion asymmetry, account for most of the observed resonances. A corrected Pidgeon and Brown scheme with the band parameters ${\gamma }_1^L=31.1\mathrm{}$, ${\gamma }_2^L=14.3\mathrm{}$, ${\gamma }_3^L=15.4\mathrm{}$, ${\kappa }^L=13.9\mathrm{}$, $E_p=21.6\mathrm{}$ eV, ${\epsilon }_g=0.2355\mathrm{}$ eV, and $\Delta =0.803\mathrm{}$ eV describes well the free-electron and phonon-assisted transition energies in both bands as well as interband and intraband magneto-optical data of other authors.