Features of the band structure and conduction mechanisms of $n$-HfNiSn semiconductor heavily Lu-doped

The crystal and electronic structures, energy, kinetic, and magnetic characteristics of $n$-HfNiSn semiconductor heavily doped with a Lu acceptor impurity in the ranges $T$ = 80–400 K and $N^{\mathrm{Lu}}_{\mathrm{A}}\approx$ 1.9 $\cdot$ 10$^{20}$ – 1.9 $\cdot$ 10$^{21}$ cm$^{-3}$ ($x$ = 0.01–0.10) at $H\le$ 10 kG is studied. The nature of the structural-defect generation mechanism leading to changes in the band gap and the degree of semiconductor compensation is determined. Its essence is the simultaneous reduction and elimination of donor-type structural defects due to the displacement of $\sim$1% of Ni atoms from the Hf $(4a)$ site, the generation of acceptor-type structural defects by substituting Ni atoms with Lu atoms at the 4c site, and the generation of donor-type defects such as vacancies at the Sn $(4b)$ site. The results of calculations of the electronic structure of Hf$_{1-x}$Lu$_x$NiSn are in agreement with experimental data. The results are discussed within the model of a heavily doped and compensated Shklovskii–Efros semiconductor.