Defect reduction in ZnSe grown by molecular beam epitaxy on GaAs substrates cleaned using atomic hydrogen

Yu, Zhonghai; Buczkowski, S. L.; Giles, N. C.; Myers, T. H.

doi:10.1063/1.118127

Cited by 34 publications

(15 citation statements)

References 24 publications

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“…[5][6][7] Two rf plasma sources were used in this study of nitrogen doping: the cryogenically cooled CARS-25 Nitrogen is the most promising dopant for p-type ZnSe, and is attractive for CdTe p-type doping, but unwanted compensating centers have limited the maximum achievable carrier densities in both of these material systems. [5][6][7] Two rf plasma sources were used in this study of nitrogen doping: the cryogenically cooled CARS-25 Nitrogen is the most promising dopant for p-type ZnSe, and is attractive for CdTe p-type doping, but unwanted compensating centers have limited the maximum achievable carrier densities in both of these material systems.…”

Section: Methodsmentioning

confidence: 99%

Nitrogen doping of ZnSe and CdTe epilayers: A comparison of two rf sources

Moldovan

Hirsch

Ptak

et al. 1998

Journal of Elec Materi

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Section: Methodsmentioning

confidence: 99%

Nitrogen doping of ZnSe and CdTe epilayers: A comparison of two rf sources

Moldovan

Hirsch

Ptak

et al. 1998

Journal of Elec Materi

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“…Recently, atomic hydrogen treatment of the GaAs substrate prior to the growth of a ZnSe layer was reported where a stacking-fault density of less than 10 4 cm Ϫ2 was obtained. 18 These Zn-or hydrogen treatments have been used only for the growth of ZnSe or ZnSSe layers, and the stackingfault density of the ZnSe layer has usually been evaluated by plan-view transmission electron microscopy ͑TEM͒ observation [10][11][12] or etch-pit density ͑EPD͒ measurements. 14 However, these treatments have not been applied to the growth of double-hetero ͑DH͒ structures on a GaAs substrate.…”

Section: Introductionmentioning

confidence: 99%

Control of the II–VI/GaAs interface reaction using hydrogen radical and Zn/As fluxes

Taike

Kawata

Kikawa

et al. 1997

Journal of Applied Physics

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Strain effects and atomic arrangements of 60° and 90° dislocations near the ZnTe/GaAs heterointerface Appl.Local interface composition and extended defect density in ZnSe/GaAs(001) and ZnSe/In 0.04 Ga 0.96 As (001) heterojunctions J.The lifetime of II-VI-based blue-green laser diodes on GaAs substrates is limited by rapid degradation in the active layers. This degradation has been observed as dark defects in the active layer during the laser operation, where defects occurred due to stacking faults that originated from the Ga 2 Se 3 compounds at the ZnSe/GaAs interface. The reported value of the density of stacking faults of the II-VI lasers was in the order of 10 5 cm Ϫ2 . To extend the lifetime, surface treatment of the GaAs substrate and control of the interface reaction are necessary. We investigated a new treatment technique using hydrogen-radical and Zn/As fluxes. We fabricated ZnSe-based double-hetero ͑DH͒ structures on a treated GaAs substrate and measured the density of dark defects in the light emitter area by electroluminescence microscopy. Chemical bonds at the interface were evaluated by x-ray photoelectron spectroscopy. A dark defect density of less than 10 5 cm Ϫ2 was obtained when the As-terminated GaAs surface was Zn treated. The Zn treatment prevented the formation of the Ga 2 Se 3 layers. When we alternated the exposure between Zn and As fluxes, excess ZnAs x interfacial layers were formed and the quality of the DH structure was unacceptable. However, hydrogen-radical exposure before and during the Zn/As treatment effectively removed the excess ZnAs x compounds, and the density of dark defects fell to 2ϫ10 4 cm Ϫ2 .

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“…using atomic hydrogen with a hydrogen pressure of 2 ϫ 10 Ϫ6 torr beam-equivalent pressure for 20 min. 7 The substrate was pre-exposed to Zn, and the samples were grown at a substrate temperature of 300°C. A special, high-temperature effusion cell was used for Cr incorporation, operating at temperatures up to 1,200°C.…”

Section: Methodsmentioning

confidence: 99%

Heavy Cr doping of ZnSe by molecular beam epitaxy

VanMil

Ptak

Bai

et al. 2002

Journal of Elec Materi

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INTRODUCTIONThe incorporation of transition-metal ions into a semiconductor host is an effective technique for producing material useful for fabricating lasers. In particular, the small crystal-field splitting found for transition-metal ions in II-VI materials allows for laser operation in the 2-5-m spectral range. 1 Lasers based on these materials are of interest for commercial and military applications for optical identification of chemicals. Many molecules have strong and unique absorption spectra in the infrared. As examples, molecules of H 2 O, CO 2, CO, N 2 O, and HCN can be accurately detected in the mid-infrared. 2,3 The incorporation of chromium into ZnSe produces an infrared-laser material that operates at room temperature and is tunable from about 2-3 m. 4 Of technological interest, the absorption band that produces the laser emission occurs at about 1,800 nm. This wavelength is currently accessible using commercial-diode lasers, and in principle, a compact and efficient laser-diode-pumped tunable solid-state laser can be built. Chromium substituting on the Zn site of the tetrahedrally coordinated II-VI lattice results in a 3d 4 electronic configuration, often referred to as Cr 2ϩ by the community, 5 and is the desired electronic configuration to allow laser fabrication. Previous incorporation of chromium into zinc selenide has focused on bulk crystals through either the addition of chromium to the melt 1 or postgrowth-isothermal diffusion. 6 The use of epitaxial-growth techniques would allow fabrication of complex heterostructures that may have advantages for certain applications. As an example, growth of ZnSe:Cr on GaAs should allow for production of integrated structures, opening the possibility of integrated pump and waveguide lasers in the same package. We present results that indicate molecular beam epitaxy (MBE) is a viable approach for incorporating optically active Cr in the ZnSe-host matrix at levels up to ϳ10 19 atoms cm Ϫ3 in epitaxial layers, comparable to that achieved for bulk techniques. EXPERIMENTAL DETAILSAll epitaxial ZnSe layers were grown in a custombuilt MBE system at West Virginia University (Morgantown, WV) on undoped, semi-insulating GaAs (100) substrates. The substrates were initially degreased, etched in H 2 SO 4 :H 2 O 2 :H 2 O (8:1:1) for 5 min at room temperature, and rinsed in flowing deionized water for 5 min. The substrates were further cleaned in situ at a substrate temperature of 400°C Epitaxial ZnSe layers were grown by molecular beam epitaxy (MBE) to study Cr incorporation with the long-term goal of demonstrating an alternate route for achieving transition-metal-doped lasers. Concentrations between 10 15 atoms cm Ϫ3 and 4 ϫ 10 20 atoms cm Ϫ3 were achieved. Secondary ion-mass spectroscopy (SIMS) concentration profiles strongly suggest that surface segregation and accumulation of Cr occurs during growth. Photoluminescence (PL) measurements indicate Cr is incorporated in the optically active Cr 2ϩ state up to levels of ϳ10 19 cm Ϫ3 . Electron paramagnetic resonance (EP...

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Defect reduction in ZnSe grown by molecular beam epitaxy on GaAs substrates cleaned using atomic hydrogen

Cited by 34 publications

References 24 publications

Nitrogen doping of ZnSe and CdTe epilayers: A comparison of two rf sources

Nitrogen doping of ZnSe and CdTe epilayers: A comparison of two rf sources

Control of the II–VI/GaAs interface reaction using hydrogen radical and Zn/As fluxes

Heavy Cr doping of ZnSe by molecular beam epitaxy

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