High-pressure bridgman grown CdZnTe for electro-optic applications

Zappettini, A.; Cerati, Lorenzo; Milani, A.; Pietralunga, Silvia Maria; Boffi, Pierpaolo; Martinelli, Mario

doi:10.1007/bf02665866

Cited by 6 publications

(4 citation statements)

References 11 publications

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“…3(a), an analogous behaviour is shown in the case of a CdS-based modulator and a GaAs-based modulator. It was previously shown by some of the authors that High Pressure Bridgman grown CdZnTe modulators present a much lower shielding effect [5] at optical powers of the order of 0.1 mW. It was also shown that, by increasing the laser power above this value, a drastic reduction of M at low modulating frequency occurred.…”

Section: Resultsmentioning

confidence: 89%

A study of the electro‐optic shielding effect in II/VI semiconductors

Zappettini

Vivarelli²,

Pietralunga³

2004

phys. stat. sol. (c)

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In this paper the effect of working temperature on the low frequency electro-optic characteristics of some II/VI crystals is studied. It is found that, by heating the modulators above 100 °C, it is possible to overcome the so called field shielding effect, i.e. the strong shielding of the externally applied electric field caused by a local field produced by photo-generated carriers. The presented measurements also show that previously suggested models for the mechanism responsible for the field effect are not valid. A new explanative model is proposed. 1 Introduction Many II/VI compounds like CdTe, CdS, and related alloys, show a high electro-optic figure of merit. This feature can be exploited in semi-insulating compensated samples, which can sustain strong electric fields. Moreover, the above mentioned materials typically show a high transparency in the IR range down to 15 microns, which allowed, for example, cadmium tellurite crystals to be employed as intracavity modulators for CO 2 lasers since the seventies [1]. In more recent years, there has been a renewal of interest towards CdTe crystals, used as electro-optic switches operating in the third window for telecommunications at λ = 1.5 µm [2].However, the electro-optic exploitation of II/VI crystals in the telecommunication range is hindered by the formation of space charge regions in the bulk material, due to carrier photo-generation from intragap levels. This results in decreasing of the electro-optic yield, through the shielding of the externally applied field [3]. This effect is particularly effective whenever the energy of the modulated optical signal approaches the band gap energy and at low modulation frequencies, where some optical switching devices, like for instance cross-connects, should preferably operate [2]. Kaminow [4] proposed an explanation for the shielding effect and linked the speed of response of the phenomenon to the carrier relaxation time, hence to the resistivity of the material. More recently, some of the authors showed that Kaminow's model could properly account for the dependence of the shielding effect on the optical power, provided that not only equilibrium carriers but also the population of photogenerated carriers is accounted, thus extending the model to the high-injection regime [3].The aim of this paper is to show that the shielding effect can be strongly reduced in electro-optic modulators based on some II/VI crystals, by heating the devices to a temperature of 100 °C. This extends effective exploitation of these modulators to the whole optical spectrum below the absorption edge of the material.

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Section: Resultsmentioning

confidence: 89%

A study of the electro‐optic shielding effect in II/VI semiconductors

Zappettini

Vivarelli²,

Pietralunga³

2004

phys. stat. sol. (c)

Self Cite

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“…The linear electro-optic constant r 41 at l ¼ 1.5 mm of Bridgman-grown Zn 0.1 Cd 0.9 Te has been measured by Zappettini et al [15] (see Table 11.1). The implementation of a Zn 0.1 Cd 0.9 Tebased electro-optic switch which reaches À30 dB of extinction ratio and sub millisecond response time has also been presented by the same authors.…”

Section: Ii-vi Semiconductor Alloymentioning

confidence: 98%

Elasto‐Optic, Electro‐Optic and Nonlinear Optical Properties

Adachi

2009

Properties of Semiconductor Alloys

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“…[1][2][3][4][5] This is attributed to several interesting properties of the materials including superior energy resolution, high absorption efficiency, and ambient environment operation. Even if this material shows excellent promise in the applications, the material quality is not fully optimized and the defects turn out obstacles for instrumentation.…”

Section: Introductionmentioning

confidence: 99%

Investigation of CdZnTe crystal defects using scanning spreading resistance microscopy

2008

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Surface electronic properties of Cd x Zn y Te were characterized through scanning spreading resistance microscopy (SSRM) and correlated IR transmittance maps. We observed the magnitude of the SSRM current is dominant by the density of surface localized Te precipitates and spatial variation of Zn content. The magnitude of the average SSRM current for forward probe bias was found to correlate strongly with the density of Te precipitates, while the variation in I-V characteristics were caused by slight p-type or n-type characteristics due to non-uniformity in Zn content of the crystal. Experimentally observed I-V characteristics were simulated using thermionic emission theory.

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High-pressure bridgman grown CdZnTe for electro-optic applications

Cited by 6 publications

References 11 publications

A study of the electro‐optic shielding effect in II/VI semiconductors

A study of the electro‐optic shielding effect in II/VI semiconductors

Elasto‐Optic, Electro‐Optic and Nonlinear Optical Properties

Investigation of CdZnTe crystal defects using scanning spreading resistance microscopy

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