Electron subbands on InP

For both $n$- and $p$-type (100) InP surfaces prepared from bulk material, we observe the conductivity of electrons in surface subbands. We report observations regarding the surface layer capacitance and link it with the conduction threshold. After some remarks on the conductivity $\sigma \left(N_s\right)$ and the field-effect mobility ${\mu }_{\mathrm{FE}}\left(N_s\right)$, we present data on the magnetoconductance ${\sigma }_{\mathrm{xx}}(H, N_s)$ and associated quantum oscillation effects. Two subbands with occupancies ${N_s}^0$ and ${N_s}^1$ are found for surface densities $N_s>1\mathrm{}\times {10}^{12}$ ${\mathrm{cm}}^{-2\mathrm{}}$. The measured occupancies allow the construction of the subband splitting $E_1-E_0\equiv E_{01}\left(N_s\right)$. We find evidence in InP for an enhanced spin splitting of the Landau levels. A final part of the paper reports on surface cyclotron resonance.