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Journal ArticleDOI

Infrared photoluminescence on molecular beam epitaxially grown Hg1-xCdxTe layers

01 Jan 1993-Semiconductor Science and Technology (IOP Publishing)-Vol. 8

AbstractHg1-xCdxTe is an important material for infrared device technology. Despite a variety of investigations on molecular beam epitaxially (MBE) grown Hg-based superlattices and modulation-doped structures, little attention has been paid to the study of the photoluminescence properties of the constituent materials. The authors report on a systematic study of infrared photoluminescene on Hg1-xCdxTe layers grown by MBE. The Fourier transform photoluminescence of Hg1-xCdxTe layers with 0.25<x<0.93 grown on (110) and (211) GaAs was investigated in the spectral range from 01 eV to 1.5 eV. Emission lines were observed with a full width at half maximum down to 15 meV. Photoluminescence and transmission properties are compared over the temperature range from 4.2 K to 300 K. The possible influence of Burstein-Moss shift, impurity bands and exponential band tails are discussed. Photoluminescence at high temperatures originates from band-to-band transitions. However, low temperature photoluminescence can be attributed either to impurity bands or to additional states due to band tails.

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Journal ArticleDOI
Abstract: Photoluminescence of HgCdTe epitaxial films and nanostructures and electroluminescence of InAs(Sb,P) light-emitting diode (LED) nanoheterostructures were studied. For HgCdTe-based structures, the presence of compositional fluctuations, which localized charge carriers, was established. A model, which described the effect of the fluctuations on the rate of the radiative recombination, the shape of luminescence spectra and the position of their peaks, was shown to describe experimental photoluminescence data quite reasonably. For InAs(Sb,P) LED nanoheterostructures, at low temperatures (4.2–100 K) stimulated emission was observed. This effect disappeared with the temperature increasing due to the resonant ‘switch-on’ of the Auger process involving transition of a hole to the spin-orbit-splitted band. Influence of other Auger processes on the emissive properties of the nanoheterostructures was also observed. Prospects of employing II–VI and III–V nanostructures in light-emitting devices operating in the mid-infrared part of the spectrum are discussed.

10 citations


Journal ArticleDOI
Abstract: Photoluminescence (PL) of HgCdTe-based hetero-epitaxial nanostructures with 50 to 1100 nm-wide potential wells was studied. The nanostructures were grown by molecular beam epitaxy on GaAs substrates. A strong degree of alloy disorder was found in the material, which led to the broadening of the PL spectra and a considerable Stokes shift that could be traced up to temperature T∼230 K. Annealing of the structures improved the ordering and led to the increase in the PL intensity. A remarkable feature of the PL was an unexpectedly small decrease of its intensity with temperature increasing from 84 to 300 K. This effect can be related to localization of carriers at potential fluctuations and to the specific character of Auger-type processes in HgCdTe-based nanostructures.

8 citations


Cites background from "Infrared photoluminescence on molec..."

  • ...A part of such broadening can be, in principle, attributed to contributions of phonon−assisted transitions [13,21], however, in many Photoluminescence of HgCdTe nanostructures grown by molecular beam epitaxy on GaAs...

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Journal ArticleDOI
Abstract: Hg 1-x Cd x Te samples with x=0.38 and 0.57 fabricated by molecular beam epitaxy, both as-grown and after annealing, were studied. Photoluminescence (PL) was measured in the temperature range 4.2 < T< 300 K. The PL peak energy was found to be less than that of the energy gap by a certain value δE that depended on temperature. This effect was attributed to recombination of excitons localized at composition non-homogeneities. An analysis was carried out that provided a way for evaluation of a non-homogeneity measure. The amplitude of the non-homogeneities was shown to decrease by about 50% as a result of post-growth annealing in a He atmosphere and Hg vapour.

7 citations


Journal ArticleDOI
Abstract: Properties of HgCdTe films grown by molecular beam epitaxy on GaAs and Si substrates have been studied by performing variable-temperature photoluminescence (PL) measurements. A substantial difference in defect structure between films grown on GaAs (013) and Si (013) substrates was revealed. HgCdTe/GaAs films were mostly free of defect-related energy levels within the bandgap, which was confirmed by PL and carrier lifetime measurements. By contrast, the properties of HgCdTe/Si films are affected by uncontrolled point defects. These could not be always associated with typical “intrinsic” HgCdTe defects, such as mercury vacancies, so consideration of other defects, possibly inherent in HgCdTe/Si structures, was required. The post-growth annealing was found to have a positive effect on the defect structure by reducing the full-widths at half-maximum of excitonic PL lines for both types of films and lowering the concentration of defects specific to HgCdTe/Si.

6 citations


Journal ArticleDOI
Abstract: We have studied the photoluminescence (PL) spectra of Cd x Hg1 − x Te/Cd y Hg1 − y Te nanohetero-structures grown by molecular beam epitaxy on CdTe/ZnTe/GaAs substrates The width of potential wells in the structures was varied within d = 12−200 nm and the material composition was changed within x ∼ 025–040 in the well and y ∼ 068–082 in the barrier layers The PL spectra of samples with d ≤ 33 nm exhibit transitions between quantum confinement levels The samples with d > 50 nm display the PL due to excitons localized on composition fluctuations, which is characteristic of Cd x Hg1 − x Te epilayers with thicknesses above 3 μm It is established that the exciton PL band in Cd x Hg1 − x Te exhibit broadening that is determined both by stochastic fluctuations of the composition and by its macroscopic inhomogeneities

4 citations


References
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Book
01 Jan 1971
Abstract: Optical processes in semiconductors , Optical processes in semiconductors , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

4,599 citations


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1,408 citations


Journal ArticleDOI
Abstract: We have used the data from 22 different studies to derive a new empirical expression for the energy band gap (Eg) of Hg1−xCdxTe: Eg =−0.302+1.93x+5.35(10−4)T(1−2x) −0.810x2+0.832x3. This expression is valid over the full composition range and for temperatures from 4.2 to 300 K. The standard error of estimate is 0.013 eV, which is at least 15% better than that of previously reported expressions.

565 citations