Contactless electroreflectance of GaNyAs1−y/GaAs multi quantum wells: The conduction band offset and electron effective mass issues
TL;DR: In this article, contactless electroreflectance spectroscopy (CER) was used to study the optical transitions in GaNyAs1−y/GaAs multi quantum well (MQW) samples with y=0.012 and 0.023.
About: This article is published in Solid State Communications.The article was published on 2006-05-01. It has received 28 citations till now. The article focuses on the topics: Effective mass (solid-state physics) & Franz–Keldysh effect.
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TL;DR: In this paper, a broadening of optical transitions in as-grown and annealed GaN, GaN 0.95 and GaN0.08 alloys were studied with photoreflectance (PR), photoluminescence (PL), and microphotoluminecence (\ensuremath{\mu}PL) in a broad range of temperatures.
Abstract: Optical transitions in as-grown and annealed GaN${}_{0.02}$As${}_{0.98}$, Ga${}_{0.95}$In${}_{0.05}$N${}_{0.02}$As${}_{0.98}$, and GaN${}_{0.02}$As${}_{0.90}$Sb${}_{0.08}$ bulklike layers have been studied with photoreflectance (PR), photoluminescence (PL), and microphotoluminescence (\ensuremath{\mu}PL) in a broad range of temperatures. The exciton binding energy and the temperature dependence of the energy gap have been determined from PR measurements. In addition, the alloy-related broadening of optical transitions has been analyzed and compared for the three alloys. The largest alloy inhomogeneities have been observed for GaN${}_{0.02}$As${}_{0.90}$Sb${}_{0.08}$. In \ensuremath{\mu}PL spectra of GaN${}_{0.02}$As${}_{0.98}$ and Ga${}_{0.95}$In${}_{0.05}$N${}_{0.02}$As${}_{0.98}$ layers measured at low temperatures and low excitation conditions, sharp PL lines of 100--300-\ensuremath{\mu}eV widths have been clearly observed \ensuremath{\sim}10--20 meV below the energy gap of these alloys. Analyzing the temperature quenching of the sharp PL lines, they have been attributed to the recombination of localized excitons trapped at deep donor (acceptor)-like states. Such lines were not well resolved for GaN${}_{0.02}$As${}_{0.90}$Sb${}_{0.08}$ layers. The analysis of thermal quenching of localized exciton emission suggests that for this alloy excitons are localized mostly on alloy content fluctuations. With the increase in the excitation power an additional PL band has been observed in \ensuremath{\mu}PL spectra at the higher-energy side. This band corresponds to the optical transitions between delocalized states which are observed in photoreflectance spectra. The emission of localized excitons without resolved sharp lines has been also observed with macro-PL measurements at low temperatures. In addition, the donor trap--valence band (DT-VB) recombination has been identified for the three alloys in macro-PL spectra. It has been clearly observed that the intensity of DT-VB recombination is the weakest for GaN${}_{0.02}$As${}_{0.90}$Sb${}_{0.08}$ alloys whereas for GaN${}_{0.02}$As${}_{0.98}$ and Ga${}_{0.95}$In${}_{0.05}$N${}_{0.02}$As${}_{0.98}$ alloys it is very similar. The observed differences between the three alloys and the role of postgrowth annealing have been analyzed and discussed in the context of the influence of III-V host on alloy inhomogeneities, formation of native point defects in III-V-N alloys, and their influence on the optical quality of III-V-N alloys.
49 citations
TL;DR: In this article, contactless electroreflectance (CER) features related to ground and excited state transitions have been observed and compared with those obtained from theoretical calculations, which were performed in the framework of the effective mass formalism model.
Abstract: Interband transitions in $\mathrm{Ga}{\mathrm{N}}_{0.02}{\mathrm{As}}_{0.98\ensuremath{-}x}{\mathrm{Sb}}_{x}∕\mathrm{Ga}\mathrm{As}$ single quantum wells (SQWs) with $0lx\ensuremath{\leqslant}0.11$ have been investigated by contactless electroreflectance (CER). CER features related to the ground and excited state transitions have been observed and compared with those obtained from theoretical calculations, which were performed in the framework of the effective mass formalism model. It has been concluded that these SQWs are type I and the conduction band offset for this material system decreases from 80% to 50% when the Sb composition is increased from 0% to 11%. It shows that the band gap discontinuity for $\mathrm{Ga}\mathrm{N}\mathrm{As}\mathrm{Sb}∕\mathrm{Ga}\mathrm{As}$ material system can be simply tuned by a change in Sb concentration.
45 citations
TL;DR: In this article, the authors present the application of contactless electroreflectance (CER) spectroscopy to study optical transitions in low dimensional semiconductor structures including quantum wells (QWs), step-like QWs, quantum dots (QDs), quantum dashes (QDashes), QDs and QDashes embedded in a QW.
Abstract: The authors present the application of contactless electroreflectance (CER) spectroscopy to study optical transitions in low dimensional semiconductor structures including quantum wells (QWs), step-like QWs, quantum dots (QDs), quantum dashes (QDashes), QDs and QDashes embedded in a QW, and QDashes coupled with a QW. For QWs optical transitions between the ground and excited states as well as optical transitions in QW barriers and step-like barriers have been clearly observed in CER spectra. Energies of these transitions have been compared with theoretical calculations and in this way the band structure has been determined for the investigated QWs. For QD and QDash structures optical transitions in QDs and QDashes as well as optical transitions in the wetting layer have been identified. For QDs and QDashes surrounded by a QW, in addition to energies of QD and QDash transitions, energies of optical transitions in the surrounded QW have been measured and the band structure has been determined for the surrounded QW. Finally some differences, which can be observed in CER and photo-reflectance spectra, have been presented and discussed for selected QW and QD structures.
34 citations
TL;DR: In this article, the authors compared the optical properties of GaInNAs/GaAs quantum wells with various nitrogen concentrations within the 10-band and 8-band kp models.
Abstract: The band structure and optical gain have been calculated for GaInNAs/GaAs quantum wells (QWs) with various nitrogen concentrations within the 10-band and 8-band kp models. Two approaches to calculate optical properties of GaInNAs/GaAs QWs have been compared and discussed in the context of available material parameters for dilute nitrides and the conduction band nonparabolicity due to the band anti-crossing (BAC) interaction between the N-related resonant level and the conduction band of a host material. It has been clearly shown that this nonparabolicity can be neglected in optical gain calculations since the dispersion of conduction band up to the Femi level is very close to parabolic for carrier concentrations typical for laser operation, i.e., 5 × 1018 cm−3. This means that the 8-band kp model when used to calculate the optical gain is very realistic and much easier to apply in QWs containing new dilute nitrides for which the BAC parameters are unknown. In such an approach, the energy gap and electron effective mass for N-containing materials are needed, instead of BAC parameters. These parameters are available experimentally much easier than BAC parameters.
34 citations
TL;DR: In this article, the authors applied contactless electroreflectance (CER) spectroscopy to study optical transitions in Ga 0.9In0.1N0.027As0.973−xSbx∕GaAs single quantum well with antimony content varying from 0% to 5.4%.
Abstract: Contactless electroreflectance (CER) spectroscopy has been applied to study optical transitions in Ga0.9In0.1N0.027As0.973−xSbx∕GaAs single quantum well (QW) with antimony content varying from 0% to 5.4%. CER features related to optical transitions between the ground and excited states have been clearly observed. Energies of the QW transitions have been matched with those obtained from theoretical calculations. It has been determined that the conduction band offset decreases from ∼55% to ∼45% with the increase in Sb content from 0% to 5.4%. This result demonstrates that the band gap discontinuity for Ga0.9In0.1N0.027As0.973−xSbx∕GaAs system can be simply tuned by a change in antimony content.
28 citations
References
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TL;DR: In this article, the authors present a comprehensive, up-to-date compilation of band parameters for the technologically important III-V zinc blende and wurtzite compound semiconductors.
Abstract: We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other.
6,349 citations
TL;DR: In this paper, a comprehensive and up-to-date compilation of band parameters for all of the nitrogen-containing III-V semiconductors that have been investigated to date is presented.
Abstract: We present a comprehensive and up-to-date compilation of band parameters for all of the nitrogen-containing III–V semiconductors that have been investigated to date. The two main classes are: (1) “conventional” nitrides (wurtzite and zinc-blende GaN, InN, and AlN, along with their alloys) and (2) “dilute” nitrides (zinc-blende ternaries and quaternaries in which a relatively small fraction of N is added to a host III–V material, e.g., GaAsN and GaInAsN). As in our more general review of III–V semiconductor band parameters [I. Vurgaftman et al., J. Appl. Phys. 89, 5815 (2001)], complete and consistent parameter sets are recommended on the basis of a thorough and critical review of the existing literature. We tabulate the direct and indirect energy gaps, spin-orbit and crystal-field splittings, alloy bowing parameters, electron and hole effective masses, deformation potentials, elastic constants, piezoelectric and spontaneous polarization coefficients, as well as heterostructure band offsets. Temperature an...
2,525 citations
TL;DR: In this paper, the authors present evidence for a strong interaction between the conduction band and a narrow resonant band formed by nitrogen states in alloys, which leads to a splitting of conduction bands into two subbands and a reduction of the fundamental band gap.
Abstract: We present evidence for a strong interaction between the conduction band and a narrow resonant band formed by nitrogen states in $\mathrm{Ga}{}_{1\ensuremath{-}x}\mathrm{In}{}_{x}\mathrm{N}{}_{y}\mathrm{As}{}_{1\ensuremath{-}y}$ alloys. The interaction leads to a splitting of the conduction band into two subbands and a reduction of the fundamental band gap. An anticrossing of the extended states of the conduction band of the $\mathrm{Ga}{}_{1\ensuremath{-}x}\mathrm{In}{}_{x}\mathrm{As}$ matrix and the localized nitrogen resonant states is used to model the interaction. Optical transitions associated with the energy minima of the two subbands and the characteristic anticrossing behavior of the transitions under applied hydrostatic pressure have been unambiguously observed using photomodulation spectroscopy. The experimental results are in excellent quantitative agreement with the model.
1,452 citations