Optical Properties of II-IV-N2 Semiconductors

Abstract

Recently, wide band gap II-IV-N 2 semiconductors such as ZnSiN 2 , and ZnGeN 2 and ZnSiGeN 2 have been synthesized, but very little is known about their band structure, optical properties, or electronic properties. Bulk crystals are hard to synthesize because high temperatures and pressures are required. The success in growing II-IV-N 2 films epitaxially by MOCVD creates interesting opportunities. The crystal structure of II-IV-N 2 compounds is orthorhombic, and when grown on r-plane sapphire can provide a suitable template for GaN growth. Optical transmission studies of the band edge of ZnSiN 2 and ZnSiGeN 2 with varying Si and Ge percentages were conducted. The indirect nature of the band gap was investigated, and prism coupling was used to obtain the refractive indices in the visible and NIR portion of the spectrum. Although the crystal symmetry was orthorhombic, the refractive indices indicated uniaxial optical properties. Optical loss measurements indicate that the films are suitable for waveguides and novel devices based on birefringent optical effects.

Electronic and lattice dynamical properties of II‐IV‐N2 semiconductors

“…Thus, we give the single-shot corrected LDA+G 0 W 0 gap of 3.19 eV which expected to be a slight underestimate. The experimental values have a significant spread from 2.67 eV [3], 3.1 eV [21,17] to 3.40±0.01 eV [14]. The largest experimental gap is obtained by PL on micron size crystals and indicates that again earlier measurements were plagued by defect absorption.…”

“…Among these, ZnGeN 2 and ZnSiN 2 and alloys of ZnSi x Ge 1−x N 2 were grown in thin film form (mostly on sapphire substrates) by a few different approaches, ranging from Cl based vapor growth [3], metalorganic chemical vapor deposition (MOCVD) [8,9], remote plasma MOCVD [10,11,12], RF-sputtering [13] at high pressure by Endo et al [2] and polycrystalline as well as small single crystals were grown by Du et al [14]. Raman spectra were measured by Viennois et al [15] on polycrystalline powders and on small single crystal needles by Peshek et al [16] Optical absorption [17], index of refraction [18], infrared reflectivity [19], magnetic properties upon Mn doping [20], and fabrication of transistors on SiC [21] were investigated for the Zn(Si,Ge)N 2 films obtained produced by Zhu et al [8]. Band structure calculations at the local density approximation (LDA) level were carried out by Limpijumnong et al [22] Misaki et al [23], Shaposhnikov et al [24] and Paudel [25] for a number of these materials but leave considerable uncertainty on the band gaps because of the shortcomings of the LDA.…”

Quasiparticle band structure of Zn-IV-N2compounds

“…The same group also reported ZnSiN 2 growth and alloy growth of ZnSi 1−x Ge x N 2 growth and these materials were investigated by a number of other collaborators determining optical properties 6,7 , transistor devices on SiC 8 , and even their suitability as magnetic semiconductor host by implantation of Mn 9 . Muth et al 6 determined band gaps from optical absorption data as a function of alloy composition in ZnSi 1−x Ge x N 2 and found it to vary between 3.1-3.2 eV for ZnGeN 2 to 4.4 eV in ZnSiN 2 . Cook et al 7 determined the indices of refraction and Mintairov et al 10 determined the infrared reflection relating to the vibrational spectrum.…”

Structural, electronic and optical properties of II–IV–N2 compounds (II = Be, Zn; IV = Si, Ge)

“…This compound has been characterized as a direct-gap semiconductor with the band gap of 2.67 eV [17]. Only few experiments were performed with ZnSiN 2 [9,18,19]. Single crystalline epitaxial ZnSiN 2 layers were obtained on nitridated sapphire substrates with the lattice parameters a = 5.34 Å, b = 6.17 Å, and c = 5.04 Å [9].…”