Cathodoluminescence characterization of Si-doped orientation patterned GaAs crystals
- PDF / 763,913 Bytes
- 6 Pages / 595.32 x 841.92 pts (A4) Page_size
- 27 Downloads / 279 Views
Cathodoluminescence characterization of Si-doped orientation patterned GaAs crystals V. Hortelano1, O. Martínez1, J. Jiménez1, M.Snure2, C.Lynch3, D. Bliss2 1
GdS OptronLab, Ed.i+d, paseo de Belén, 1, Universidad de Valladolid, Valladolid
47011, Spain 2
Air Force Research Laboratory, Sensors Directorate, Wright Patterson AFB, Dayton
OH, U.S.A 3
Photonic Products Group Inc, Northvale, NJ, U.S.A ….
ABSTRACT Orientation patterned (OP)-GaAs crystals are attractive materiasl for mid-infrared and terahertz lasers sources, using non linear optics frequency conversion from shorter wavelength sources. The optical propagation losses are critical to the fabrication of these sources; among the causes of optical losses the generation of defects and the incorporation of impurities must play a relevant role. The control of the incorporation of impurities and defects is, therefore, crucial to improve the performance of the OP-GaAs crystals as non linear optical materials. We present herein a cathodoluminescence (CL) analysis of OP-GaAS crystals intentionally doped with Si, in order to understand the incorporation paths of Si in the OP-GaAs crystals. INTRODUCTION Mid infrared (mid-IR) and terahertz (THz) frequency sources are very important for IR spectroscopy for remote gas sensing, IR countermeasures for aircraft protection, and THz imaging. In spite of this technological interest, mid-IR laser sources are scarcely available. Among the more attractive candidates for those laser sources, the non linear optical conversion by quasi-phase matching (QPM) with GaAs crystals is taking a significant role (1, 2). The high non linear optical coefficient of GaAs makes it an ideal candidate as a mid-IR material, as it is transparent in the spectral window of interest (0.9-17 m). Nevertheless; GaAs is an isotropic material, and therefore one cannot periodically pole it for modulating the non linear optical coefficient. The alternative to this is the fabrication of gratings with periodic alternation of the non linear optic coefficient. This can be done by periodically reversing the crystal orientation, forming the so-called orientation patterned GaAs crystals (OP-GaAs), which are periodic gratings of [001] and [00-1] oriented crystals. The epitaxial fabrication of OPGaAs crystals has demonstrated second harmonic generation, optical parametric generation, amplification and oscillation in the spectral window of 1 to 12 µm [3]. These crystals are inserted in an optical parametric oscillator (OPO), allowing laser sources with wavelengths ranging from 2 m to the THz range. Fast growth of the periodic GaAs structures is achieved by hydride vapour phase epitaxy (HVPE) (4-6). To reach sufficient conversion efficiency, the optical propagation losses must be minimized, which demands a material free of defects. In particular, the absortion by free
carriers is one of the main sources of optical propagation losses. The main residual defect is Si; therefore, the study of structures intentionally doped with Si is very useful to understand its incorpor
Data Loading...
