The features of hole resonant tunneling in Si1-xGex /Si double barrier structures

The features of hole resonant tunneling in Si_0.8Ge_0.2 double barrier structures are studied both experimentally and theoretically. The theoretical calculations are based on the principles proposed in a recent study on the origin of resonant tunneling and its temperature dependence. The calculation results explain the different trends of variations with the temperature for the characteristic currents and voltages, if the first resonance is attributed to hh tunneling via the first hh subband and the second resonance to lh tunneling via first lh subband. The calculated peak current density for different structure also agrees well with the experiments in the low temperature region. The calculations show that at current resonance, the tunneling level can be higher or lower than the quasi Fermi-level in the spacer. The distinctly different temperature dependence of the first and second resonances can be understood by considering the different population of the hh and lh bands in the spacer region and the temperature dependences of E_f and effective masses