Optical absorption edge in doped and undoped ZnSe crystals

Baillou, J.; Bugnet, P.; Daunay, J.; Auzary, C.; Poindessault, R.

doi:10.1016/0022-3697(80)90199-7

Cited by 35 publications

(3 citation statements)

References 8 publications

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“…[1][2][3][4] These shifts in zinc chalcogenides are markedly stronger than, e.g., in cadmium chalcogenides, group-IV materials, and many III-V compounds. The available experimental data on the temperature dependence of the lowest (1s) exciton line, E 1s (T), or the associated fundamental band gap, E g (T), in ZnS, [5][6][7][8][9] ZnSe, 5,[10][11][12][13][14][15] and ZnTe [16][17][18] bulk crystals or layers is in the range of cryogenic to room temperatures. Most of these E(T) data sets [5][6][7][8][9][10][11][12][13][14][15][16][17][18] are not adequate, however, for detailed analytical and numerical descriptions or reliable extrapolations above room temperature.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of exciton peak energies in ZnS, ZnSe, and ZnTe epitaxial films

Pässler

Griebl

Riepl

et al. 1999

Journal of Applied Physics

136

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High-quality ZnS, ZnSe, and ZnTe epitaxial films were grown on ͑001͒-GaAs-substrates by molecular beam epitaxy. The 1s-exciton peak energy positions have been determined by absorption measurements from 2 K up to about room temperature. For ZnS and ZnSe additional high-temperature 1s-exciton energy data were obtained by reflectance measurements performed from 300 up to about 550 K. These complete E 1s (T) data sets are fitted using a recently developed analytical model. The high-temperature slopes of the individual E 1s (T) curves and the effective phonon temperatures of ZnS, ZnSe, and ZnTe are found to scale almost linearly with the corresponding zero-temperature energy gaps and the Debye temperatures, respectively. Various ad hoc formulas of Varshni type, which have been invoked in recent articles for numerical simulations of restricted E 1s (T) data sets for cubic ZnS, are discussed.

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Section: Introductionmentioning

confidence: 99%

Temperature dependence of exciton peak energies in ZnS, ZnSe, and ZnTe epitaxial films

Pässler

Griebl

Riepl

et al. 1999

Journal of Applied Physics

136

View full text Add to dashboard Cite

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“…18 ͑At 90 K, the ZnSe band gap is 2.8 eV, so that the absorption coefficient ϭ10 3 cm Ϫ1 for the HeCd hϭ2.806 eV.͒ Fig. ͑No GaAs luminescence is observed for these spectra.͒ Photoexcitation via a HeCd laser includes the heterointerface since the laser is absorbed only slightly in the ZnSe but strongly within the first ten nanometers of the GaAs.…”

Section: Resultsmentioning

confidence: 95%

Deep level formation at ZnSe/GaAs(100) interfaces

Raisanen¹

1995

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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We have used low energy cathodo- and photoluminescence spectroscopies to characterize the formation of charge states deep within the ZnSe band gap and localized near the ZnSe/GaAs interface. These deep levels are a common feature of the ZnSe/GaAs heterostructure and depend sensitively on growth conditions and post-growth annealing. Here we report in situ measurements of deep level formation near the ZnSe/GaAs interface during post-growth annealing and their dramatic dependence on the initial epitaxical growth conditions. We used 1–2 keV electron beam energies in tandem with HeCd and HeNe excitation to obtain emission spectra characteristic of the free ZnSe surface, the ZnSe bulk, and the ZnSe/GaAs(100) interface. Annealing in ultrahigh vacuum in the 300–500 °C range produces a new emission feature at 1.9–2.0 eV whose intensity increases exponentially with temperature, exhibiting an activation energy of 1.10±0.08 eV. This feature appears enhanced (suppressed) in structures fabricated in Se(Zn)-rich growth, and its intensity may therefore be related to the Zn vacancy concentration or the Ga indiffusion. These results emphasize the importance of local composition in the formation of interface deep level defects and their subsequent effects on luminescence efficiency and heterojunction stability.

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“…We annealed the specimens in 5 min annealing cycles at increasing temperatures from 250°C to as high as 500°C. The GaAs absorption coefficient 18 is larger than the ZnSe absorption coefficient at 2.8 eV by a factor of 100 ͑i.e., ϳ10 5 vs 10 3 cm Ϫ1 ͒, 19 and the sensitivity of the S-1 photomultiplier at 2.8 eV is lower than that at 1.5 eV by a factor of ϳ6. Previous low energy electron diffraction ͑LEED͒ measurements show a predominant ͑2ϫ1͒ mixed with c(2ϫ2) pattern, and the Se cap layers were desorbed between 200 and 300°C, which is consistent with the literature.…”

Section: Methodsmentioning

confidence: 88%

Internal photoinjection and deep level luminescence at ZnSe/GaAs heterointerfaces

Yang

Brillson

Raisanen

et al. 1996

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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We have used photoluminescence spectroscopy to measure the relative intensity of the ZnSe and GaAs near band edge ͑NBE͒ emissions at ZnSe/GaAs interfaces fabricated by molecular beam epitaxy under different growth conditions. Using a HeCd laser to excite free electron-hole pairs near the buried heterointerface, we found systematic variations in the NBE relative intensity as a function of the Zn to Se beam pressure ratio used to grow the ZnSe epilayers. The results are in good agreement with the predictions of a simple expression for free carrier injection across the interface due to internal photoemission. In such a process, laser excitation results in free carriers which can move from GaAs to ZnSe over barriers due to the heterojunction band offsets and recombine across the band gap or via deep levels. The variation of such internal photoemission with different growth conditions supports the previously reported dependence of the ZnSe/GaAs band offset on the local interface composition.

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Optical absorption edge in doped and undoped ZnSe crystals

Cited by 35 publications

References 8 publications

Temperature dependence of exciton peak energies in ZnS, ZnSe, and ZnTe epitaxial films

Temperature dependence of exciton peak energies in ZnS, ZnSe, and ZnTe epitaxial films

Deep level formation at ZnSe/GaAs(100) interfaces

Internal photoinjection and deep level luminescence at ZnSe/GaAs heterointerfaces

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