Tunneling study of surface quantization inn−PbTe

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Using electron tunneling through $n$-type PbTe-oxide-Pb junctions, we have measured some electronic properties of the (100) surface accumulation layer at the PbTe-oxide interface. Three energy levels, resulting from quantization of the electronic motion normal to the surface, are observed in a sample having $n=1.2\ifmmode\times\else\texttimes\fi{}{10}^{18}$ /${\mathrm{cm}}^{2}$. The energies of these three levels are ${E}_{0}=42$ meV, ${E}_{1}=19$ meV, and ${E}_{2}=6$ meV below the conduction band edge. From the magnetotunneling data we obtain ${g}^{*}=29\ifmmode\pm\else\textpm\fi{}3$ and ${m}^{*}=(0.069\ifmmode\pm\else\textpm\fi{}0.008){m}_{0}$ for the ground-state subband. In addition, the Landau levels in the ground-state subband do not cross the Landau levels in the excited-state subband. The interaction between the Landau levels removes the degeneracy at the crossover and a splitting, $\ensuremath{\Delta}E\ensuremath{\approx}4$ meV, has been observed.