Search for semiconducting materials among 18-electron half-Heusler alloys

A high throughput search for semiconductors among 153 half-Heusler phases with 18 valence electrons was performed. The alloys considered were as follows: III–X–XV, IV–X–XIV, IV–IX–XV, V–IX–XIV, and V–VIII–XV, wherein the particular groups of the elements were confined as shown: III (Sc, Y, La, Ga, In), IV (Ti, Zr, Hf), V (V, Nb, Ta), VIII (Fe, Ru, Os), X (Ni, Pd, Pt), XIV (Ge, Sn, Pb), and XV (As, Sb, Bi). The generalized gradient approximation (GGA) and modified Becke–Johnson GGA (MBJGGA) approaches were employed in order to calculate the band structures as well as determine the types and widths of band gaps in the materials. Furthermore, the strength of spin–orbit coupling in some systems was discussed based on the heavy- and light-hole energy split-offs. Some compounds are expected to be topological insulators, e.g., the novel Pd-based arsenide (LuPdAs). The set of 24 novel semiconductors following the ‘10 kBT rule’, which suggests their potential for application in thermoelectrics, was revealed. The results of this work should encourage further experimental efforts in synthesis of novel half-Heusler phases.