Conduction mechanisms in ferroelectric wurtzite Al1− <i>x</i> Hf <i>x</i> N heterovalent alloys

Abstract

Characteristic electrical transport analysis of textured ferroelectric wurtzite Al1−xHfxN (x = 0.00,  0.07,  0.14,  0.28,  0.42) thin films was performed using temperature-dependent leakage current measurements on Mo/Al1−xHfxN/Mo/SiC capacitors. A unified analysis couples (i) slope-magnitude comparisons against the theoretical forms for conduction mechanisms of Poole–Frenkel, Schottky, and fixed-range hopping, (ii) extractions of effective energy barriers via Arrhenius fits with variable applied E-field when applicable, and (iii) low-field ohmic fits. Low-field response is ohmic for all x, while compositions with increasing x show an increase in the E-field value at which ohmic-to-non-ohmic onset occurs. The unified analysis shows a trend of high-field electrical transport shifting from interface limited (Schottky) to bulk limited (Poole–Frenkel) conduction with increasing x. A resulting conduction mechanism map illustrates this gradual composition-driven change from interface to bulk limited. This is consistent with HfAl acting as deep trap states, though mechanistic details require additional investigation.