Tunneling study of surface quantization inn−PbTe

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 $n=1.2\mathrm{}\times {10}^{18}$ /${\mathrm{cm}}^2$. The energies of these three levels are $E_0=42\mathrm{}$ meV, $E_1=19\mathrm{}$ meV, and $E_2=6\mathrm{}$ meV below the conduction band edge. From the magnetotunneling data we obtain $g^{*}=29\mathrm{}\pm 3$ and $m^{*}=(0.069\mathrm{}\pm 0.008)m_0$ 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, $\Delta E\approx 4$ meV, has been observed.