Analysis of hydrogen-doped lithium nitride admittance data

Abstract

Admittance data taken at seven temperature from ≈24 to 182°C on a hydrogen-doped lithium nitride single crystal with gold electrodes perpendicular to the c axis are analyzed using non-linear complex least-squares fitting, and the results are presented as three-dimensional perspective plots. An equivalent circuit used in previous fitting is shown to be inadequate and an improved one, which requires an inductance to yield good results at high frequencies and temperatures, is proposed and used. Thes circuit is partly based on previous small-signal analysis and thus many of its parameter values, estimated from the complex least-squares fitting, may be interpreted in terms of more basic properties of the electrode/material/electrode system. The activation enthalpy for conduction is found to be ≈0.223 eV. In addition, an interface capacitance as well as a diffuse double layer capacitance are identified. The material appears to show both an electrode reaction and heterogeneous adsorption, and the dominant mobile carriers in either the interface layer or possibly in the entire material are tentatively identified as electrons. The very high calculated mobility of the charge carriers decreases exponentially with increasing temperatures.