Tunneling Spectroscopic Study of the Impurity Band of (000) Valley of Germanium

抄録

Analyzing I–V characteristics of the direct current component of a reversely biased germanium tunnel diode, the density of states and the electronic self-energy in the impurity band associated with (000) subsidiary valley were investigated. The d²I⁄dV²−V curves for As doped samples (Nd=5×10¹⁸ and 1.5×10¹⁹ cm⁻³) showed that the density of states has a dip between the impurity band and the main band. In the case of Sb doped sample (N_d=5×10¹⁸ and 1.3×10¹⁹ cm⁻³), there was little evidence for the dip, but there existed only a long tail going down continuously below the main band. The imaginary part of the self-energy in the impurity band was found to decay exponentially into the forbidden band in both materials. The results were in good agreement with the measurements of the localized spin through the zero bias conductance anomaly.