Cyclotron-resonance determination of band offset in a PbTe quantum well

For quantum wells composed of narrow-band-gap materials the subbands exhibit nonparabolic dispersion. We exploit this property in analyzing far-infrared cyclotron resonance in a PbTe quantum well confined by a lattice-matched ${\mathrm{Pb}}_{0.894}$ ${\mathrm{Eu}}_{0.106}$ ${\mathrm{Se}}_{0.100}$ ${\mathrm{Te}}_{0.00}$ barrier. Observation of cyclotron resonance permits simultaneous measurement of carrier density and cyclotron mass, whose energy dependence leads to a determination of the band offset at the interfaces. Energy-band calculations based on the two-band model indicate that the gap centers of the well and barrier are offset such that the valence-band barrier is increased by about 100 meV.