Electrical studies of single‐barrier Hg1−xCdxTe heterostructures

We report an experimental study of the electrical properties of single‐barrier Hg_(1−x)Cd_xTe heterostructures grown by molecular‐beam epitaxy. At high temperature, the measured current is interpreted to be the sum of thermionic and tunneling hole currents. This analysis is applied to data from each of three samples, yielding values of the HgTe–CdTe valence‐band discontinuity between 290±50 and 390±75 meV at 300 K. In all three samples, data taken over the range 190–300 K are consistent with a valence‐band offset which decreases at lower temperatures. Current–voltage curves are taken at 4.2 K, yielding a novel single‐barrier negative differential resistance (NDR) due to electron tunneling. Theoretical simulations indicate that ΔE_v must be <100 meV at 4.2 K to produce NDR.