Insights about AlP (001) Surface Reconstructions: A Density Functional Theory Study

Abstract

Using first-principles calculations and thermodynamics criteria, we investigated the structural and electronic properties of the AlP (001) surface. We considered 18 different possible surface reconstructions. They were chosen by considering the stable surfaces reported for other III−V semiconductors. According to the results, five stable surface reconstructions were found: at Al-rich conditions, the (2 × 4) mixed dimer and the δ (2 × 6) surfaces, at intermediate conditions, the δ (2 × 4), and β2 (2 × 4) surface reconstructions, and at P-rich conditions, the (2 × 2) P-dimer. Electronic properties were evaluated by calculating the density of states. The results show that the surfaces have semiconductor behavior, except for the (2 × 2) P-dimer, which is metal. Electron localization function (ELF) line profiles demonstrate the covalent nature of the Al−P and P−P bonds, while the Al−Al interaction is metallic. Our results provide insights into the possible surface reconstructions in the AlP compounds. Also, the results suggest that the surfaces are good candidates to be employed in the development of diluted magnetic semiconductors.

Evidence of Half-Metallicity in the AlP/CrP (001) Interface: A First-Principles Study

“…The IFE plot is depicted in Figure 5a. In our previous report, 28 five different surface reconstructions were reported as thermodynamically stable for the AlP (001) surface. Our results show that the (2 × 2)-P dimer (orange surface) is stable at Al-poor conditions for the entire range of μ Cr , and the β2 (2 × 4) reconstruction (red surface) is stable at Al-poor and Alintermediated conditions for all Cr chemical potential.…”

“…AlP grows in the zinc-blende (ZB) structure, with a calculated lattice constant of a = 5.51 Å, in agreement with previous reports. 28 On the other hand, CrP growth in orthorhombic structure with cell parameters a = 5.36, b = 3.114, and c = 6.018 Å. 41 However, Pask et al 29 propose the metastable zincblende phase, with a calculated cell parameter of a = 5.42 Å as the favorable growth onto the AlP (001) surface; for more details, see the SI.…”

“…Thermodynamic Stability. In our previous work, we investigated the thermodynamic stability of different AlP (001) surfaces 28 by the surface formation energy (SFE) formalism. Here, we considered the same formalism but included the contribution of Cr atoms as follows where A is the surface area, E slab is the total energy of each specific model, and E ref is the energy of an arbitrary reference.…”

“…23−26 Also, it has been doped with magnetic materials to form diluted magnetic semiconductors (DMS). 27 Recently, we had 28 (2 × 4) mixed dimer, the δ(2 × 6), the δ(2 × 4), the β2(2 × 4), and the (2 × 2)-P dimer. Pask et al 29 proposed six different ferromagnetic compounds based on Cr and Mn with zinc-blende structures as promising candidates for spintronic applications.…”