Influence of the lattice mismatch strain on the surface morphology of ZnMgTe/ZnTe/ZnMgTe electro-optical waveguide structure

Abstract

ZnMgTe/ZnTe waveguide is a high potential electro‐optical device. Thick and high Mg composition cladding layers are required for high optical performance waveguides. However, adding Mg would increase the lattice mismatch between ZnMgTe and ZnTe which would cause dislocation defects and generate asperities at interfaces. In this article, influence of the lattice mismatch strain to the waveguide surface morphology was studied. Waveguide structures were prepared by molecular beam epitaxy. The surface morphologies were observed using atomic force microscope and propagation loss of the waveguides were studied. Total of 0.5–0.7 μm asperities were observed on the surface of waveguides with 20% of Mg composition and 1.2 μm of the total cladding layer thickness. The asperities on the surface became larger (1.0–1.2 μm) when the Mg composition increased to 40%. The propagation loss of the waveguide was suppressed to 7 dB by tuning the growth parameters and the resulting interface roughness.

Surface Morphology and Electronic Properties of SnTe Films Prepared by Molecular Beam Epitaxy

“…The experiments were performed with a V80H MBE system (VG UK) equipped with Te and Sn elemental sources. [26][27][28][29][30] The surface morphologies of the samples were measured by atomic force microscopy (AFM, JEOL JSMP-5200), and the electrical properties were measured by Hall effect measurements (ACCENT HL5500PC). All of the measurements were performed at room temperature, and a permanent magnet of AE0.32 T was used to create the magnetic field in the Hall effect measurements.…”

“…The experiments were performed with a V80H MBE system (VG UK) equipped with Te and Sn elemental sources. [ 26–30 ]…”

Surface modification of a-plane sapphire substrates and its effect on crystal orientation of ZnTe layer

“…II-VI compound semiconductors are important in a broad range of optoelectronic devices including ultraviolet (UV) applications, 1,2) green light emitting devices, 3,4) photovoltaics, 5,6) X-ray high-energy sensors, 7,8) optical waveguides, [9][10][11][12] and terahertz devices. 13,14) In particular, zinc telluride (ZnTe) has been extensively studied to characterize its physical properties, because transparency in the visible region and a large electro-optical (EO) effect can be expected simultaneusly.…”

“…13,14) In particular, zinc telluride (ZnTe) has been extensively studied to characterize its physical properties, because transparency in the visible region and a large electro-optical (EO) effect can be expected simultaneusly. [10][11][12][13][14] In recent years, terahertz-wave-detecting devices utilizing the EO effect of ZnTe have been widely studied. 13,14) For utilization in terahertz-wave-detecting devices based on ZnTe thin films, the control of the film thickness and crystallographic orientation is important; a high EO effect from (110)-or (111)-oriented ZnTe thin films is desirable.…”