A new single step process for synthesis and growth of ZnGeP2 crystal

Wang, T.Y.; Sivakumar, R.; Rai, D.K.; Hsu, Wei-Feng; Lan, C.W.

doi:10.1016/j.jcice.2007.12.011

Cited by 18 publications

(9 citation statements)

References 11 publications

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confidence: 65%

“…ZGP's generation efficiency surpasses that of high-quality and high-resistivity wafers of GaAs and GaP across the infrared, including the datacoms C-band around 1550 nm. This study complements the recent resurgence of interest in ZGP as a nonlinear material driven by high-quality growth [6,7].Undoped ZGP single crystals were grown by the horizontal gradient freeze technique [6]. Samples were cut in the (110) plane and double-side polished for optical transmission measurements.…”

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confidence: 79%

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Broadband terahertz pulse emission from ZnGeP_2

et al. 2012

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Optical rectification is demonstrated in (110)-cut ZnGeP 2 (ZGP) providing broadband terahertz (THz) generation. The source is compared to both GaP and GaAs over a wavelength range of 1150 nm to 1600 nm and peak intensity range of 0.5 GW/cm 2 to 40 GW/cm 2 . ZGP peak-to-peak field amplitude is larger than in the other materials due to either lower nonlinear absorption or larger second order nonlinearity. This material is well suited for broadband THz generation across a wide range of infrared excitation wavelengths.Over the last decade, broadband sources of intense THz pulses have received significant attention due to the possibility of accessing a diverse range of light-matter interactions and the potential for creating high-speed electronics. For a recent review of the progress see Ref.[1] and references therein. Large-area zincblende ̅ crystals are commonly used in time-domain terahertz spectroscopy as sources and electrooptic (EO) samplers [2] due to large second-order nonlinear coefficients. A common issue with materials like GaAs and ZnTe is that the optimum wavelength for THz and optical velocity matching is poorly positioned with respect to the onset of two-photon absorption.Here we generate broadband THz pulses in ZnGeP2, a chalcopyrite (pnictide) crystal with ̅ symmetry, by optical rectification. Optical rectification is a second-order nonlinear optical process that generates a transient D.C. polarization, which typically creates THz radiation for short excitation pulses. In previous work, ZnGeP2 has only been used as a source of narrow-band and tuneable THz radiation through parametric down conversion [3,4]. This work verifies that ZGP has a suitable coherence length, high laserdamage threshold [3] and nonlinear figure-of-merit [5] for optical rectification. ZGP's generation efficiency surpasses that of high-quality and high-resistivity wafers of GaAs and GaP across the infrared, including the datacoms C-band around 1550 nm. This study complements the recent resurgence of interest in ZGP as a nonlinear material driven by high-quality growth [6,7].Undoped ZGP single crystals were grown by the horizontal gradient freeze technique [6]. Samples were cut in the (110) plane and double-side polished for optical transmission measurements. Sample thicknesses are 0.33 mm and 0.93 mm for the short and long crystals respectively. The orientation of the crystals was verified by electron paramagnetic resonance (EPR), ensuring that the z-axis is in the plane of the plate. EPR measures the phosphorus hyperfine signal associated with the zinc-vacancy acceptor in asgrown ZGP, differentiating the 100 and 001 directions [8]. ZGP is birefringent due to a ~2% lattice compression in the z-axis, which complicates the THz generation for pump polarizations that are not parallel or perpendicular to this axis. Measurements were performed at normal incidence with the crystal rotated in the plane to maximize the THz signal. The rotation results in the pump being polarized perpendicular to the z-axis of the ZGP crystal, such th...

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confidence: 65%

mentioning

confidence: 79%

Broadband terahertz pulse emission from ZnGeP_2

et al. 2012

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“…In order to overcome some problems in ZGP crystals growth, the single crystals are grown by various methods such as the vertical Bridgman (VB) [9], vertical gradient freezing (VGF) [10], horizontal gradient freezing (HGF) [11], liquid encapsulated Czochralski (LEC) [12], highpressure vapor transport (HPVT) [13] methods, etc. For the present, the most conventional techniques for the growth of ZGP single crystals remain the VB and HGF methods [14][15][16]. All these techniques have some shortcomings, however, such as inhomogeneity of the temperature field, large thermal stress in the crystals, high-density dislocations, twins, cracks and second phase precipitates.…”

Section: Introductionmentioning

confidence: 99%

Growth and characterization of ZnGeP2 single crystals by the modified Bridgman method

Zhao

Zhu

Zhao

et al. 2008

Journal of Crystal Growth

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“…The ZnGeP 2 crystals used in this experiment were grown by the modified Bridgman technique [5]. All the samples were bulk ZnGeP 2 crystals in irregular shapes.…”

Section: Etching and Etch Pitsmentioning

confidence: 99%

“…It can be used for parametric infrared frequency shifting of radiation, second-harmonic generation and optical parametric oscillators (OPOs) [1][2][3][4][5]. Highquality bulk ZnGeP 2 crystal is mainly grown using the vertical Bridgman and gradient freezing techniques [4][5][6][7]. The as-grown crystals in both of the techniques are generally without the directionality.…”

Section: Introductionmentioning

confidence: 99%