Structural and optical properties of high-quality ZnTe homoepitaxial layers

Chang, Jae-Soo; Cho, M. W.; Wang, H. M.; Wenisch, H.; Hanada, Takashi; Yao, Takafumi; Satô, Kenji; Oda, Osamu

doi:10.1063/1.1290155

Cited by 33 publications

(22 citation statements)

References 12 publications

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“…Thus far, the ZnTe-based materials have been studied by some research groups. For example, growth and characterization of homo-epitaxial ZnTe [2], MgZnSeTe quaternaries [3], quantum well structures [4], and yellow-to-green LEDs [5][6][7] were reported. However, no lasing operation had been achieved though such so many efforts had been made.…”

Section: Introductionmentioning

confidence: 99%

Yellow–green lasing operations of ZnCdTe/MgZnSeTe laser diodes on ZnTe substrates

Nomura

Manoshiro

Kikuchi

et al. 2006

Physica Status Solidi (b)

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ZnCdTe/MgZnSeTe laser diodes (LDs) were fabricated on ZnTe substrates by molecular beam epitaxy. The LDs were characterized under single short pulse current injections at low temperature. Yellow -green single-mode lasing emissions at 564 nm were successfully obtained, for the first time. The threshold current density (J th ) at 100 K was 2.8 kA/cm 2 . The full width at half maximum value of the lasing emission peak was 1.1 meV (0.29 nm). From the temperature dependency of the J th , it was confirmed that the lasing operations were obtained up to 170 K. The characteristic temperature value was estimated to be 228 K.

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Section: Introductionmentioning

confidence: 99%

Yellow–green lasing operations of ZnCdTe/MgZnSeTe laser diodes on ZnTe substrates

Nomura

Manoshiro

Kikuchi

et al. 2006

Physica Status Solidi (b)

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“…1 Introduction ZnTe is a promising material for pure-green light emitting diodes (LEDs), green laser diodes (LDs) [1,2] and electro-optic (EO) devices [3][4][5]. In order to develop these ZnTe based applications, large diameter single crystal substrates are necessary.…”

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confidence: 99%

ZnTe single crystal growth by the liquid encapsulated pulling method

Asahi¹,

Yabe²,

Satô³

2004

Physica Status Solidi (b)

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Large diameter ZnTe single crystals were grown by the liquid-encapsulated pulling method using a double crucible. Crystals of around 80 mm in diameter and 40 mm in length were reproducibly obtained by this method. Both 〈100〉 and 〈110〉 crystals were successfully grown. The strong facet growth was observed when the shoulder part of the bulk was formed. Rectangular facet growth was observed in 〈100〉 growth and hexagonal facet growth was observed in 〈110〉 growth. The etch pit density of the grown crystal was lower than 10000 cm -2 and the strain in the crystal was lower than that of modified liquid encapsulated Kyropoulos method.1 Introduction ZnTe is a promising material for pure-green light emitting diodes (LEDs), green laser diodes (LDs) [1, 2] and electro-optic (EO) devices [3][4][5]. In order to develop these ZnTe based applications, large diameter single crystal substrates are necessary. It is, however, well known that growing II-VI semiconductor single crystals is very difficult owing to inferior physical properties [6]. The liquid encapsulated Czochralski (LEC) method has not been successfully applied to II-VI materials. We believe that the large temperature gradient of the LEC method [7] causes the difficulty of the single crystal growth owing to the the instability of the melt and generation of crystal defects. In our previous work, ZnTe single crystals were successfully obtained by modified liquid encapsulated Kyropoulos [8] (LEK) method using the small temperature gradient [9]. Our LEK crystals, however, had large strain and were sometimes cracked because of the difference in the thermal expansion coefficient between ZnTe and the encapsulant since the grown crystals were cooled in the encapsulant.In order to solve this problem, we tried to grow ZnTe single crystals by the liquid-encapsulated pulling method using a double crucible as the new growth method improved from the LEK and the LEC methods. In this paper, crystal growth of ZnTe by the double-crucible liquid-encapsulated pulling (DCP) method is reported.

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“…1 Introduction ZnTe is a promising material for optical devices [1,2] and electro-optic (EO) devices [3][4][5] due to its physical property. Only low-brightness pure-green LEDs have been obtained and green laser diodes (LDs) using compound semiconductors have been underdeveloped.…”

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confidence: 99%

Reduction of Te inclusions in ZnTe single crystals by thermal annealing

Yabe¹,

Asahi²,

Satô³

2004

phys. stat. sol. (c)

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ZnTe crystals grown from the melt have Te inclusions. The wafer annealing under Zn pressure was carried out to reduce Te inclusions in ZnTe wafers. It was found that the cyclic annealing process, where heating and cooling was done cyclically over a temperature range of several tens of degrees, was effective to annihilate the Te inclusions. We obtained the inclusion-free ZnTe crystals by optimising the temperature cycling condition.1 Introduction ZnTe is a promising material for optical devices [1, 2] and electro-optic (EO) devices [3][4][5] due to its physical property. Only low-brightness pure-green LEDs have been obtained and green laser diodes (LDs) using compound semiconductors have been underdeveloped. Thus the performance of optical devices in green region is poor compared with red and blue regions. ZnTe is expected as the material for the optical devices because it is a direct transition semiconductor with 2.26 eV energy gap at room temperature. ZnTe is also interesting as an EO crystal because of its high EO coefficient compared with the other compound semiconductors.For development of these ZnTe based devices, we grew large diameter single crystals by the melt growth method [6,7]. The grown crystals had many Te inclusions of around 5 µm in diameter. Because the composition at the congruent point largely deviates from the stoichiometrical composition to the Te excess region and the composition on the solidus line approaches the stoichiometrical composition as decreasing temperature [8], Te inclusions are inevitably precipitated in the cooling process after crystal growth. It is essential to use high quality crystals in order to fabricate the devices with high performance and high reliability, so that it is necessary to prepare ZnTe wafers without inclusions. In the case of CdTe and CdZnTe, pressure of Cd and/or Te was controlled to reduce inclusions during crystal growth [9]. To reduce inclusions in ZnTe, crystal growth under controlled Zn pressure in the furnace is also effective. It is, however, difficult to grow crystals under Zn pressure because quartz ampoules, conventionally used for sealing source materials for crystal growth, are not used owing to the high melting point of ZnTe and there are not suitable materials.So, in our previous work, wafer annealing under Zn pressure was applied in the quartz ampoule at lower temperatures than the melting point. It was found that the Te inclusions disappeared after the wafer annealing under proper Zn pressure and at proper annealing temperature, as long as evaluation was carried out by an optical microscope [10].We did not, however, scrutinize the crystallinity at the points where Te inclusions disappeared. In this work, therefore, we evaluated the point where the Te inclusion existed by a scanning electron microscope (SEM). Furthermore we investigated the proper thermal annealing process to improve the crystallinity of ZnTe single crystals.

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Structural and optical properties of high-quality ZnTe homoepitaxial layers

Cited by 33 publications

References 12 publications

Yellow–green lasing operations of ZnCdTe/MgZnSeTe laser diodes on ZnTe substrates

Yellow–green lasing operations of ZnCdTe/MgZnSeTe laser diodes on ZnTe substrates

ZnTe single crystal growth by the liquid encapsulated pulling method

Reduction of Te inclusions in ZnTe single crystals by thermal annealing

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