Vertical Bridgman growth and characterization of large ZnGeP2 single crystals

Xia, Shengji; Wang, Meng; Yang, Chunhui; Lei, Zuotao; Zhu, Guoli; Yao, Baoquan

doi:10.1016/j.jcrysgro.2010.11.062

Cited by 14 publications

(3 citation statements)

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“…The main method of preparing ZnGeP 2 single crystal is melt directional solidification such as the vertical Bridgman (VB) method [3], vertical gradient freezing (VGF) method [4], and horizontal gradient freezing (HGF) method [5]. However, crystal defects, such as micro-crack induced by anisotropic thermal expansion [6], growth striations induced by temperature oscillation [7,8], and point defects that lead to the deviation of stoichiometry always found in the as-grown ZnGeP 2 single crystals [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…However, crystal defects, such as micro-crack induced by anisotropic thermal expansion [6], growth striations induced by temperature oscillation [7,8], and point defects that lead to the deviation of stoichiometry always found in the as-grown ZnGeP 2 single crystals [3][4][5]. Until now, there are many theoretical [9,10] and experiments reports [11][12][13][14] on identifying the types of defects existed in as-grown ZnGeP 2 crystals and their contributions to the broad absorption band, as well as growth and post-treatment studies [15][16][17] on reducing the optical absorptions in the region of 1-2 mm.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Growth improvement and quality evaluation of ZnGeP2 single crystals using vertical Bridgman method

Zhang

Tao

Wang

et al. 2012

Journal of Crystal Growth

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Growth improvement and quality evaluation of ZnGeP2 single crystals using vertical Bridgman method

Zhang

Tao

Wang

et al. 2012

Journal of Crystal Growth

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“…ZnGeP 2 specifically has been grown through the latter class of methods: the vertical Bridgman method [1, 64,65], vertical gradient freeze [66], and horizontal gradient freeze [2] techniques.…”

Section: Chalcopyrite Growthmentioning

confidence: 99%

Chalcopyrite Semiconductors as Sources for Terahertz Spectroscopy

Rowley¹

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This dissertation summarizes a first effort to address the suitability of chalcopyrite structured semiconductors for efficient and broadband terahertz (THz) pulse emission by optical rectification. The experiments demonstrate that ZnGeP 2 , a chalcopyrite semiconductor showing improved growth quality in recent decades [1,2], is a promising source for THz spectroscopy while also addressing general fundamental questions concerning the nonlinear generation process in chalcopyrite semiconductors. Beyond ZnGeP 2 , the potential of other chalcopyrite structured semiconductors for THz emission is examined in the context of calculated phase-matching characteristics, onset pump wavelength of multiphoton absorption, and tabulated second-order nonlinear coefficients. Based on these, CdGeP 2 is determined to show particular promise among semiconductors as a THz source when pumped at or near the fiber laser line of 1.55 μm. The orientation dependence of THz optical rectification efficiency is examined in tetragonal birefringent ZnGeP 2 , compared to that of cubic GaP, and modeled based on the second-order nonlinear tensor, while accounting for birefringence. These results demonstrate the significant effects of birefringence on THz emission efficiency while defining the most efficient orientations for generation and can be generalized to other chalcopyrite semiconductors; the general approach is applicable to other uniaxial birefringent crystals. Experimental mapping of generated THz pulses is presented over a broad pump tuning range (1120-2480 nm) in 3 mm thick ZnGeP 2 crystals. This mapping, for two distinct and efficient orientations, demonstrates the moderate angle tunability of phase mismatch achievable in chalcopyrite crystals; the data also continuously demonstrate the effects of phase mismatch on the temporal and spectral THz pulse waveform. Finally, pump-intensity dependence of emission is presented for three crystal lengths, showing the effects of near-infrared nonlinear optical absorption and THz free-carrier absorption. Measurements, modeling, and calculation of characteristic lengths provide insight into the upper limit of pulse intensity and crystal length for generation of intense terahertz pulses without detriment to the bandwidth. Direct comparison of generation efficiency from GaP and ZnGeP 2 is also measured for reference.

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