Epitaxial growth and electronic structure of a layered zinc pnictide semiconductor, β-BaZn2As2

Abstract

BaZn2As2 is expected for a good p-type semiconductor and has two crystalline phases of an orthorhombic α phase and a higher-symmetry tetragonal β phase. Here, we report high-quality epitaxial films of the tetragonal β-BaZn2As2 were grown on single-crystal MgO (001) substrates by a reactive solid-phase epitaxy technique. Out-of-plane and in-plane epitaxial relationships between the film and the substrate were BaZn2As2 (00l )//MgO (001) and BaZn2As2 [200]//MgO [200], respectively. The full-widths at half maximum were 0.082 o for a 008 out-of-plane rocking curve and 0.342 o for a 200 in-plane rocking curve. A step-and-terrace structure was observed by atomic force microscopy. The band gap of β-BaZn2As2 was evaluated to be around 0.2 eV, which is much smaller than that of a family compound LaZnOAs (1.5 eV). Density functional theory calculation using the Heyd-Scuseria-Ernzerhof hybrid functionals supports the small band gap.

Drastic improvement of Curie temperature by chemical pressure in N-type diluted magnetic semiconductor Ba(Zn,Co)$$_{2}$$As$$_{2}$$

“…1 a, we show polycrystalline X-ray diffraction patterns of Sr-doped (Ba Sr )(Zn Co ) As ( x = 0.05, 0.10 and 0.15) and Sb-doped Ba(Zn Co ) (As Sb ) ( x = 0.05 and 0.10). We should mention that BaZn As exhibit two different crystal structures, the low-temperature orthorhombic phase -BaZn As (space group Pnma) 29 and the high-temperature tetragonal phase -BaZn As (space group I4/mmm) as a semiconductor with a bandgap 0.2 eV 30 , 31 . Both p -type DMS (Ba,K)(Zn,Mn) As and n -type DMS Ba(Zn,Co) As were achieved in the high temperature tetragonal phase 17 , 28 .…”

Ba(Zn1−2xMnxCux)2As2: A Bulk Form Diluted Ferromagnetic Semiconductor with Mn and Cu Codoping at Zn Sites

“…2(b) as an example. The values of energy gap E g are between 0.031 and 0.048 eV, which are about an order of magnitude smaller than that of the parent compound BaZn 2 As 2 25. We have conducted Hall effect measurement on Ba(Zn 0.75 Mn 0.125 Cu 0.125 ) 2 As 2 , but the large resistivity prevents us to accurately determine the carrier density.…”

“…Among them, the T C of (Ba, K)(Zn, Mn) 2 As 2 single crystal has been reported to reach 230 K24. (Ba, K)(Zn, Mn) 2 As 2 was synthesized by doping Mn and K into the parent compound β -BaZn 2 As 2 which is a direct gap (0.2 eV) semiconductor25, where the substitution of Mn for Zn and K for Ba introduces spins and hole carriers, respectively.…”

Narrow Bandgap in β-BaZn2As2 and Its Chemical Origins

“…Recently, first-principles calculations for the -and -BaZn2As2 phases reported that they have complicated and highlyanisotropic electronic structures due to the unusual cation-anion and anion-anion hybridizations; 28 however, it does not provide an explanation for the extreme narrow bandgap of -BaZn2As2. Further, the previously-reported bandgap value 25 is not so reliable due to the interference of the substrate optical absorption, and no other experimental data on its electronic structure has been provided.…”