Electronic structure, chemical bonding and optical properties of the nonlinear optical crystal ZnGeP₂by first-principles calculations

Abstract

Using the plane wave pseudopotential method within density-functional theory, we have theoretically investigated the structural, electronic, chemical bonding and optical properties of the chalcopyrite semiconductor ZnGeP 2 . It is found that ZnGeP 2 has an indirect band gap of 1.222 eV. The covalent character of the bonds in ZnGeP 2 crystal is verified by Mulliken population. By analyzing the optical properties including the dielectric function, refractive index, extinction coefficient, reflectivity spectrum and absorption coefficient, we indicate that ZnGeP 2 is a promising mid-IR optical material, which is in good agreement with the available experimental results.

Predicting Solid State Material Platforms for Quantum Technologies

“…In comparison, the experimentally reported band gap is somewhat larger at 2.0 eV [79]. ZnGeP 2 crystallizes in a non-polar space group, possesses no magnetic moment, exhibits strongly covalent bonds, and has been reported as an excellent mid-IR transparent crystal material that is suitable for nonlinear optical applications [78]. Importantly, it is possible to integrate sources of photon quantum states based on nonlinear optics with ZnGeP 2 [80].…”

“…For the ABC 2 structures, the elements Ga, Cd, In and Zn can occupy the A-site, Cu, Sn, Ag and Ge take the B-site, while S, Se, Te, P or As may reside at the C site. Most of the predicted compounds include at least one toxic element with one exception: ZnGeP 2 (mp-4524) in a chalcopyrite-like tetragonal crystal structure with an indirect band gap of 1.2 eV [78] as reported in the MP database. In comparison, the experimentally reported band gap is somewhat larger at 2.0 eV [79].…”

Origin of the anomalous trends in band alignment of GaX/ZnGeX2 (X = N, P, As, Sb) heterojunctions

“…These new compounds have the same number of valence electrons as the original III-V compounds, so they are expected to obey the octet rule with the same semiconductor characters. However, although some ternary compounds such as ZnGeN 2 and ZnGeP 2 have been synthesized and are predicted to have interesting properties for novel applications such as nonlinear optical devices [9,10] , the electronic band structures of these compounds are poorly understood. For example, it is not clear what the relative positions of the conduction band minimums (CBMs) and valence band maximums (VBMs) are between GaX and ZnGeX 2 after Ga is replaced by its neighboring Zn and Ge elements and how the band offsets change as the anion atomic number increases from N to P to As to Sb.…”