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RESEARCH PRODUCT

Comparativeab initiostudy of half-Heusler compounds for optoelectronic applications

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For the advancement of optoelectronic applications, such as thin-film solar cells or laser diodes, there is a strong demand for new semiconductor materials with tailored structural and electronic properties. The eight-electron half-Heusler compounds include many promising materials with a big variety of lattice constants and band gaps. So far only a small number of them have been investigated. With the help of ab initio calculations, we have studied all possible configurations of ternary 1:1:1 compounds in the half-Heusler structure. We have investigated 648 half-Heusler materials, including compounds of the types I-I-VI, I-II-V, I-III-IV, II-II-IV, and II-III-III. For all compounds, we have optimized the lattice constant and determined the most stable arrangement of elements on the half-Heusler lattice sites. Preferred configurations and semiconductivities are compared for the different half-Heusler types. A discussion of the lattice geometries provides a parameter-free function for estimating the lattice constants. The calculated band gaps and lattice constants are used to select potential substitute materials for CdS in the buffer layer of ${\text{CuInSe}}_{2}$ and $\text{Cu}(\text{In},\text{Ga}){\text{Se}}_{2}$ thin-film solar cells.