Current-Voltage Characteristics of nBn Structures Based on Mercury Cadmium Telluride Epitaxial Films

The current - voltage characteristics of nBn structures based on HgCdTe grown by molecular beam epitaxy (MBE) on GaAs substrates in the temperature range 9-300 K were experimentally studied. The choice of technological parameters of nBn structures was determined by the possibilities of creating infrared detectors for the 3-5 mu m spectral range (MWIR). Structures with various compositions (from 0.67 to 0.84) and thicknesses (from 120 to 300 nm) of the barrier layers were studied. It was established that the composition in the barrier layer exerts the greatest influence on the type of current-voltage characteristics. For a composition equal to 0.84, the current density at small reverse bias is much lower than that for structures with lower compositions in the barrier. For structures with pronounced temperature dependence of the current density, activation energies were found that ranged from 66 to 123 meV. Studies of nBn structures with various electrode areas have shown that for high current densities, leakage along the lateral walls plays an important role. Possible mechanisms for the formation of current - voltage characteristics in MWIR nBn structures based on MBE HgCdTe are discussed.