Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 1992
The authors report a complete and systematic study based on photoluminescence (PL) and deep-level... more The authors report a complete and systematic study based on photoluminescence (PL) and deep-level transient spectroscopy (DLTS) measurements performed on fully strained or relaxed SiGe/Si single heterostructures (SH) and fully strained double heterostructures (DH) grown by rapid thermal chemical vapor deposition (RTCVD). First of all, the well-resolved free excitonic PL transition, clearly observed in high-quality pseudomorphic SiGe single layers grown by RTCVD, is used to acceed to the structural and interfacial characteristics of thin strained SiGe layers in the DH. The main results show the striking efficiency of a Si epitaxial capping layer in reducing drastically the SiGe surface recombination and the influence of the alloy disorder. In fact, this disorder must be taken into account to explain the broadening of the excitonic line. Moreover, the measurement of the no-phonon line full width at half-maximum is reported to be useful to control and analyze when the layer starts to r...
Page 1. Journal Citation (to be inserted by the publisher) Copyright by Trans Tech Publications S... more Page 1. Journal Citation (to be inserted by the publisher) Copyright by Trans Tech Publications Study of the wet re-oxidation annealing on SiO2/4H-SiC (0001) interface properties by AR-XPS measurements A. Ekoué 1 , O. Renault 1 , T. Billon 1 , L. Di Cioccio 1 and G. Guillot 2 ...
Abstract. Exploring the possibility of doping InP with transition metals other than iron to get s... more Abstract. Exploring the possibility of doping InP with transition metals other than iron to get semi-insulating material with good and stable electrical properties is very important from a practical point of view. We have grown InP crystals doped with elements from the second long period (Nb, MO, Ru, Rh and Pd) by the high-pressure gradient freeze method or by the liquid encapsulated Czochralski technique. Samples have been characterised electrically by Hall effect measurements and chemically analysed by spark source mass spectroscopy ...
ABSTRACT A photoreflectance study of excitonic transitions in cubic GaN grown on cubic SiC pseudo... more ABSTRACT A photoreflectance study of excitonic transitions in cubic GaN grown on cubic SiC pseudo-substrates is reported. The determination of the temperature dependence of the two exciton energies is allowed by the rather low transition widths. Comparison of the two PR transition energies and widths with theoretical calculation as a function of biaxial strain indicates that the lowest PR excitonic transition is composed of both contributions of light hole and heavy hole valence band related excitons. The width of this transition is increasing as the residual strain in the layer increases the splitting between light and heavy hole valence bands.
Admittance and deep level transient spectroscopy (DLTS) measurements were taken on n- and p-type ... more Admittance and deep level transient spectroscopy (DLTS) measurements were taken on n- and p-type Schottky diodes in order to determine the activation energies of both shallow (aluminium and nitrogen) and deep levels in 6H SiC epitaxial layers. A dependence on the lattice sites is found for N and suggested for Al. For N the activation energies are 82 and 137
Electrical and optical junction space-charge spectroscopies, photoluminescence, and electron para... more Electrical and optical junction space-charge spectroscopies, photoluminescence, and electron paramagnetic resonance are used to investigate the charge states of Co present in n-type InP and to characterize the deep levels occuring in such Co doped materials. Electron paramagnetic resonance and photoluminescence results indicate unambiguously that the Co2+ charge state is present in n-type material substitutional to indium. Only one deep level at EV +0.24 eV is detected with a concentration similar to Co doping. The (EV +0.24 eV) level is identified with the (Co2+→Co3++eCB) charge state change mainly on the analysis of its optical cross sections σ0n (hν) and σ0p (hν). Optical transitions are well interpreted as transitions from the Co2+ ground state (4A2) to the Γ point minimum of the conduction band for σ0n (hν) and from the valence band to the Co2+ ground (4A2) and excited state (4T2) for σ0p (hν). The value of the ionization energy for Co2+ in InP (1.16 eV) is shown to agree quite...
Single and multiple InAs/InP strained quantum wells have been grown by hydride vapor-phase epitax... more Single and multiple InAs/InP strained quantum wells have been grown by hydride vapor-phase epitaxy (HVPE). A compact set of vent/run valves monitored by manifold switches and a computer allowed the vapor species to be changed. InAs growth times of 4–24 s followed by etching times of 7–14 s, in an InCl, HCl, and H2 atmosphere, were used to control the thickness and interface abruptness. Low-temperature photoluminescence (PL) spectra have revealed emissions either in the form of a single peak or well-resolved multiple peaks attributed to monolayer variation in quantum-well thickness. The thinnest well obtained, observed for the first time by HVPE, has a PL energy transition at 1.28 eV. Experimental data agree well with theoretical calculations, taking into account strain effects on band structure and effective masses. The full widths at half maximum indicate good interfacial abruptness.
Lattice-matched and strained InxGa1−xAs/In0.52Al0.48As single quantum wells with x=0.53 and x=0.6... more Lattice-matched and strained InxGa1−xAs/In0.52Al0.48As single quantum wells with x=0.53 and x=0.60 have been studied by the optical modulation technique of photoreflectance (PR) at room temperature. The measurements have allowed the observation of interband transitions from the heavy- and light-hole valence subbands to the conduction subbands. The PR data have been adjusted with a least-squares fit to the first-derivative functional form. The energetic positions of the optical transitions deduced from the fit have been compared with theoretical values obtained by an envelope function model calculation including strain effects. The best adjustment allowed the determination of the conduction-band offset parameter Qc which is found equal to 0.71±0.07 for the lattice-matched and strained compositions.
We show how the height dispersion of self-organized InAs/InP(001) quantum islands emitting at 1.5... more We show how the height dispersion of self-organized InAs/InP(001) quantum islands emitting at 1.55 μm was reduced by optimizing the epitaxial growth parameters. Low height dispersion was obtained when the InAs deposit thickness was much greater than the critical thickness for two-dimensional/three-dimensional growth mode transition, and when adatom surface diffusion was favored by increasing the growth temperature or reducing the arsenic pressure during the InAs growth. When these growth conditions are not respected, the multicomponent photoluminescence spectrum obtained is explained through the common interpretation of island height varying with monolayer fluctuation. In optimized growth conditions, the multicomponent spectrum obtained is interpreted as emission from fundamental and excited levels of InAs islands with low height dispersion. Transmission electron microscopy (TEM) imaging shows that these InAs islands are stick-like, 50–100 nm in length and 22±1.2 nm in width. Cross-...
The positions of the acceptor level of vanadium in GaAs, GaP, and InP are estimated. This level i... more The positions of the acceptor level of vanadium in GaAs, GaP, and InP are estimated. This level is found to be at about Ec−0.14 eV in GaAs and about Ec−0.8 eV in GaP. It is above the conduction band edge in InP. These positions in the three hosts are in agreement with the trends proposed by Ledebo and Ridley. The finding of a very high acceptor level of vanadium in GaAs does not allow to explain the semi-insulating behavior of GaAs:V. Other possible compensating centers are considered.
ABSTRACT Deep level transient spectroscopy (DLTS) and Laplace-DLTS (L-DLTS) have been used to inv... more ABSTRACT Deep level transient spectroscopy (DLTS) and Laplace-DLTS (L-DLTS) have been used to investigate defects in an n-type GaAs before and after exposure to a dc hydrogen plasma (hydrogenation). DLTS revealed the presence of three prominent electron traps in the material in the temperature range 20–300 K. However, L-DLTS with its higher resolution enabled the splitting of two narrowly spaced emission rates. Consequently four electron traps at, EC—0.33 eV, EC—0.36 eV, EC—0.38 eV and EC—0.56 eV were observed in the control sample. Following hydrogenation, all these traps were passivated with a new complex (presumably the M3), emerging at EC—0.58 eV. Isochronal annealing of the passivated material between 50 and 300 °C, revealed the emergence of a secondary defect, not previously observed, at EC—0.37 eV. Finally, the effect of hydrogen passivation is completely reversed upon annealing at 300 °C, as all the defects originally observed in the reference sample were recovered.
2004 24th International Conference on Microelectronics (IEEE Cat. No.04TH8716)
Conductance DLTS measurements performed on 4H-SiC MESFETs shows "hole-like" traps peaks... more Conductance DLTS measurements performed on 4H-SiC MESFETs shows "hole-like" traps peaks. These levels are associated with surface states. The conductance measurements are interpreted using a model previously developed for GaAs MESFETs which involves the presence of an interface conducting layer between the channel and the passivating layer (SiC/SiO2 in our case).
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 1992
The authors report a complete and systematic study based on photoluminescence (PL) and deep-level... more The authors report a complete and systematic study based on photoluminescence (PL) and deep-level transient spectroscopy (DLTS) measurements performed on fully strained or relaxed SiGe/Si single heterostructures (SH) and fully strained double heterostructures (DH) grown by rapid thermal chemical vapor deposition (RTCVD). First of all, the well-resolved free excitonic PL transition, clearly observed in high-quality pseudomorphic SiGe single layers grown by RTCVD, is used to acceed to the structural and interfacial characteristics of thin strained SiGe layers in the DH. The main results show the striking efficiency of a Si epitaxial capping layer in reducing drastically the SiGe surface recombination and the influence of the alloy disorder. In fact, this disorder must be taken into account to explain the broadening of the excitonic line. Moreover, the measurement of the no-phonon line full width at half-maximum is reported to be useful to control and analyze when the layer starts to r...
Page 1. Journal Citation (to be inserted by the publisher) Copyright by Trans Tech Publications S... more Page 1. Journal Citation (to be inserted by the publisher) Copyright by Trans Tech Publications Study of the wet re-oxidation annealing on SiO2/4H-SiC (0001) interface properties by AR-XPS measurements A. Ekoué 1 , O. Renault 1 , T. Billon 1 , L. Di Cioccio 1 and G. Guillot 2 ...
Abstract. Exploring the possibility of doping InP with transition metals other than iron to get s... more Abstract. Exploring the possibility of doping InP with transition metals other than iron to get semi-insulating material with good and stable electrical properties is very important from a practical point of view. We have grown InP crystals doped with elements from the second long period (Nb, MO, Ru, Rh and Pd) by the high-pressure gradient freeze method or by the liquid encapsulated Czochralski technique. Samples have been characterised electrically by Hall effect measurements and chemically analysed by spark source mass spectroscopy ...
ABSTRACT A photoreflectance study of excitonic transitions in cubic GaN grown on cubic SiC pseudo... more ABSTRACT A photoreflectance study of excitonic transitions in cubic GaN grown on cubic SiC pseudo-substrates is reported. The determination of the temperature dependence of the two exciton energies is allowed by the rather low transition widths. Comparison of the two PR transition energies and widths with theoretical calculation as a function of biaxial strain indicates that the lowest PR excitonic transition is composed of both contributions of light hole and heavy hole valence band related excitons. The width of this transition is increasing as the residual strain in the layer increases the splitting between light and heavy hole valence bands.
Admittance and deep level transient spectroscopy (DLTS) measurements were taken on n- and p-type ... more Admittance and deep level transient spectroscopy (DLTS) measurements were taken on n- and p-type Schottky diodes in order to determine the activation energies of both shallow (aluminium and nitrogen) and deep levels in 6H SiC epitaxial layers. A dependence on the lattice sites is found for N and suggested for Al. For N the activation energies are 82 and 137
Electrical and optical junction space-charge spectroscopies, photoluminescence, and electron para... more Electrical and optical junction space-charge spectroscopies, photoluminescence, and electron paramagnetic resonance are used to investigate the charge states of Co present in n-type InP and to characterize the deep levels occuring in such Co doped materials. Electron paramagnetic resonance and photoluminescence results indicate unambiguously that the Co2+ charge state is present in n-type material substitutional to indium. Only one deep level at EV +0.24 eV is detected with a concentration similar to Co doping. The (EV +0.24 eV) level is identified with the (Co2+→Co3++eCB) charge state change mainly on the analysis of its optical cross sections σ0n (hν) and σ0p (hν). Optical transitions are well interpreted as transitions from the Co2+ ground state (4A2) to the Γ point minimum of the conduction band for σ0n (hν) and from the valence band to the Co2+ ground (4A2) and excited state (4T2) for σ0p (hν). The value of the ionization energy for Co2+ in InP (1.16 eV) is shown to agree quite...
Single and multiple InAs/InP strained quantum wells have been grown by hydride vapor-phase epitax... more Single and multiple InAs/InP strained quantum wells have been grown by hydride vapor-phase epitaxy (HVPE). A compact set of vent/run valves monitored by manifold switches and a computer allowed the vapor species to be changed. InAs growth times of 4–24 s followed by etching times of 7–14 s, in an InCl, HCl, and H2 atmosphere, were used to control the thickness and interface abruptness. Low-temperature photoluminescence (PL) spectra have revealed emissions either in the form of a single peak or well-resolved multiple peaks attributed to monolayer variation in quantum-well thickness. The thinnest well obtained, observed for the first time by HVPE, has a PL energy transition at 1.28 eV. Experimental data agree well with theoretical calculations, taking into account strain effects on band structure and effective masses. The full widths at half maximum indicate good interfacial abruptness.
Lattice-matched and strained InxGa1−xAs/In0.52Al0.48As single quantum wells with x=0.53 and x=0.6... more Lattice-matched and strained InxGa1−xAs/In0.52Al0.48As single quantum wells with x=0.53 and x=0.60 have been studied by the optical modulation technique of photoreflectance (PR) at room temperature. The measurements have allowed the observation of interband transitions from the heavy- and light-hole valence subbands to the conduction subbands. The PR data have been adjusted with a least-squares fit to the first-derivative functional form. The energetic positions of the optical transitions deduced from the fit have been compared with theoretical values obtained by an envelope function model calculation including strain effects. The best adjustment allowed the determination of the conduction-band offset parameter Qc which is found equal to 0.71±0.07 for the lattice-matched and strained compositions.
We show how the height dispersion of self-organized InAs/InP(001) quantum islands emitting at 1.5... more We show how the height dispersion of self-organized InAs/InP(001) quantum islands emitting at 1.55 μm was reduced by optimizing the epitaxial growth parameters. Low height dispersion was obtained when the InAs deposit thickness was much greater than the critical thickness for two-dimensional/three-dimensional growth mode transition, and when adatom surface diffusion was favored by increasing the growth temperature or reducing the arsenic pressure during the InAs growth. When these growth conditions are not respected, the multicomponent photoluminescence spectrum obtained is explained through the common interpretation of island height varying with monolayer fluctuation. In optimized growth conditions, the multicomponent spectrum obtained is interpreted as emission from fundamental and excited levels of InAs islands with low height dispersion. Transmission electron microscopy (TEM) imaging shows that these InAs islands are stick-like, 50–100 nm in length and 22±1.2 nm in width. Cross-...
The positions of the acceptor level of vanadium in GaAs, GaP, and InP are estimated. This level i... more The positions of the acceptor level of vanadium in GaAs, GaP, and InP are estimated. This level is found to be at about Ec−0.14 eV in GaAs and about Ec−0.8 eV in GaP. It is above the conduction band edge in InP. These positions in the three hosts are in agreement with the trends proposed by Ledebo and Ridley. The finding of a very high acceptor level of vanadium in GaAs does not allow to explain the semi-insulating behavior of GaAs:V. Other possible compensating centers are considered.
ABSTRACT Deep level transient spectroscopy (DLTS) and Laplace-DLTS (L-DLTS) have been used to inv... more ABSTRACT Deep level transient spectroscopy (DLTS) and Laplace-DLTS (L-DLTS) have been used to investigate defects in an n-type GaAs before and after exposure to a dc hydrogen plasma (hydrogenation). DLTS revealed the presence of three prominent electron traps in the material in the temperature range 20–300 K. However, L-DLTS with its higher resolution enabled the splitting of two narrowly spaced emission rates. Consequently four electron traps at, EC—0.33 eV, EC—0.36 eV, EC—0.38 eV and EC—0.56 eV were observed in the control sample. Following hydrogenation, all these traps were passivated with a new complex (presumably the M3), emerging at EC—0.58 eV. Isochronal annealing of the passivated material between 50 and 300 °C, revealed the emergence of a secondary defect, not previously observed, at EC—0.37 eV. Finally, the effect of hydrogen passivation is completely reversed upon annealing at 300 °C, as all the defects originally observed in the reference sample were recovered.
2004 24th International Conference on Microelectronics (IEEE Cat. No.04TH8716)
Conductance DLTS measurements performed on 4H-SiC MESFETs shows "hole-like" traps peaks... more Conductance DLTS measurements performed on 4H-SiC MESFETs shows "hole-like" traps peaks. These levels are associated with surface states. The conductance measurements are interpreted using a model previously developed for GaAs MESFETs which involves the presence of an interface conducting layer between the channel and the passivating layer (SiC/SiO2 in our case).
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