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  • American Institute of Physics (AIP)  (24)
  • 1
    Electronic Resource
    Electronic Resource
    Comparative photoluminescence study of hydrogenation of GaAs, AlxGa1−xAs, and AlAs (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 475-477 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-temperature photoluminescence (PL) measurements of GaAs, AlxGa1−xAs, and AlAs samples grown by molecular beam epitaxy have been carried out to study the effects of hydrogen diffusion. Following exposure to a hydrogen plasma, the PL spectra of AlxGa1−xAs change. In particular, direct gap AlxGa1−xAs shows a strong increase in the total PL intensity whereas the PL spectra of indirect gap AlxGa1−xAs show an increase in the excitonic-related recombinations after hydrogenation; the binary compounds present less dramatic changes. We interpret our results in terms of hydrogen passivation of deep and shallow centers (DX), whose densities are higher for aluminum concentration near the direct to the indirect gap crossover.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101857
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  • 2
    Electronic Resource
    Electronic Resource
    Nanocrystal size modifications in porous silicon by preanodization ion implantation (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2182-2184 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A tuning of the nanocrystal sizes in porous silicon has been obtained by self-ion implantation in p-type silicon wafers before the anodization treatment. Sample porosity, luminescence spectra, Raman scattering, and transmission electron microscopy have been used to determine the structure of porous silicon samples. A porosity increase, a blue shift of the luminescence peak, a widening of the phonon resonance, and a decrease in the size features revealed by transmission electron microscopy (TEM) images are observed by increasing the ion implantation dose. It is suggested that this effect results from the increased resistivity of the Si wafer caused by the ion implantation damage. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112755
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  • 3
    Electronic Resource
    Electronic Resource
    Strain and alloying effects on the electronic and vibrational properties of InyAl1−yAs on InP (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 470-477 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence and Raman measurements have been carried out as a function of In content (y) in relaxed and strained InyAl1−yAs alloys grown by molecular-beam epitaxy on InP. From the analysis of photoluminescence data near the lattice matched condition a reliable energy-gap dependence on In content for the strained material has been derived. From this the Bir–Pinkus electronic deformation potentials at the lattice matched condition have been determined. The Raman results for the relaxed material have been interpreted in the framework of the modified random element isodisplacement theory, yielding the localized Al mode in InAs, the gap In mode in AlAs, and quadratic dependences versus y for the different optical-phonon frequencies (AlAs-like and InAs-like). Optical-phonon deformation potentials have been calculated within ab initio theory for AlAs and successfully used to fit the AlAs-like phonon frequencies in strained InyAl1−yAs. Some problems have been found in interpreting the InAs-like strained phonon frequencies. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360628
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  • 4
    Electronic Resource
    Electronic Resource
    Spectroscopic investigation of electroluminescent porous silicon (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 1118-1126 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Light-emitting porous silicon films have been obtained by anodic etching p-type Si samples in a HF-ethanol solution. Porous Si samples efficiently luminesce at room temperature in the visible region. A degradation of the luminescence intensity with time is observed. Micro-Raman spectroscopy of free-standing porous silicon layers indicates phonon confinements as well as a strong laser heating effects. The surface chemical composition and the effect of electron-beam irradiation has been investigated through Auger spectroscopy. The Si LVV Auger transition dominates the spectrum, even in aged samples. The Si line shape gives evidence of a covalent bond between the porous Si surface atoms and some adsorbed species. A prolonged electron irradiation results in a strong variation of the surface chemical composition, with an anomalous carbon accumulation. Gold thin films have been deposited on the porous Si surface to form metal-semiconductor junctions. Schottky diodes with large rectifying ratio, ideality factor, and series resistance are obtained. When the junction is forward biased, electroluminescence is observed. Electroluminescence degrades with time while the current does not. When the junction is reverse biased a significant photocurrent is obtained. The results are discussed in the framework of the surface state emission model for the luminescence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356495
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  • 5
    Electronic Resource
    Electronic Resource
    Self-interstitial mechanism for Zn diffusion-induced disordering of GaAs/AlxGa1−xAs (x=0.1−1) multiple-quantum-well structures (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 3769-3781 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaAs/AlxGa1−xAs multiple-quantum-well (MQW) structures with identical well thicknesses but with different Al contents x in the barrier (x≈0.1, 0.2, 0.45, and 1) were grown by molecular-beam epitaxy to study the impurity-induced disordering mechanism. The disordering of the structures is observed directly by transmission electron microscopy on cleaved wedges of the sample, by the secondary electron imaging mode of scanning electron microscopy, and by secondary-ion-mass spectroscopy after Zn diffusions at 575 °C during different times (1, 4, 9, and 16 h). The results show that the totally and partially disordered regions are always behind the Zn diffusion front. The partially disordered extent depends on x. As x increases, the disordering rate increases due to the increase in Zn diffusivity. The effect of high Zn concentration is investigated by photoluminescence and by Raman scattering measurements. The systematical analysis of the photoluminescence spectra of the MQW structures diffused for different times and of the photoluminescence spectra taken on different depths below the sample surface makes it possible to describe the physical processes occurring during Zn diffusion. The column-III vacancies are created at the sample surface. They diffuse into the bulk of the sample where they are filled by other defects. Using the x-ray-diffraction technique, an expansion of the lattice constant in the region behind the Zn diffusion front was observed. This is due to a supersaturation of column-III interstitials. During the incorporation of Zn into the crystal lattice, column-III interstitials are generated. These interstitials could be responsible for the enhancement of the Al-Ga interdiffusion. The important role of the electric field at the p-n junction formed by Zn diffusion is discussed. The negatively charged column-III vacancies and the positively charged column-III interstitials are confined, respectively, on the n and p sides of the p-n junction. The results give evidence for the self-interstitial mechanism of Zn diffusion-induced disordering in GaAs/AlGaAs MQW structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352883
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  • 6
    Electronic Resource
    Electronic Resource
    Annealing effects on Si-doped GaAs grown on high-index planes by molecular-beam epitaxy (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 3151-3157 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A photoluminescence study of the effects of annealing on Si-doped (∼1016 cm−3) GaAs grown on (311)A-, (111)A-, (111)B-, and (100)-oriented substrates by molecular-beam epitaxy has been performed. The anneal temperatures were 873, 973, and 1098 K. All the anneals were of 24 h duration. Detailed assessment of the low-temperature photoluminescence spectra suggests that site switching (Si switching from Ga site to As site) only occurs in the n-type samples [(100) and (111)B samples] and not in the p-type ones [(111)A and (311)A samples].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356994
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  • 7
    Electronic Resource
    Electronic Resource
    Thermal conversion of n-type GaAs:Si to p type in excess arsenic vapor (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 3887-3891 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Annealing in excess arsenic vapor at 650 °C introduces thermal conversion of n-type Si-doped GaAs samples (n = 1.3 × 1018 cm−3) into p type. The observations are made by current-voltage and electron-beam induced current measurements. The donor concentration on the n side near the junction decreases after annealing. We present a comparison between the photoluminescence spectra of samples annealed under different conditions and an analysis of depth profile of the photoluminescence spectra. Our results underline the important role of gallium vacancies and gallium vacancy-silicon donor complex in the thermal conversion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349196
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  • 8
    Electronic Resource
    Electronic Resource
    Role of point defects in the silicon diffusion in GaAs and Al0.3Ga0.7As and in the related superlattice disordering (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 2225-2237 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The mechanism of silicon diffusion in GaAs, Al0.3Ga0.7As, and the silicon diffusion-induced layer disordering of multiquantum wells have been studied by photoluminescence, secondary-ion-mass spectroscopy, and transmission electron microscopy across a corner of a wedge-shaped sample. The diffusion source was a grown in highly Si-doped layer. The main photoluminescence properties of point defects in GaAs and Al0.3Ga0.7As are reviewed to interpret the experimental data. The depth profile of the photoluminescence allows the spatial correlation between the luminescence spectra and the Si concentration profile obtained from secondary-ion-mass-spectroscopy measurements. On the basis of the photoluminescence results, the physical processes occurring during the Si diffusion are discussed. Frenkel defects (pairs of element-III vacancies and interstitials) are generated in the highly Si-doped region. The element-III interstitials rapidly diffuse towards the surface where they react with the element-III vacancies generated at the surface when annealing is performed in an external As pressure. This induces a supersaturation of element-III vacancies in the Si-doped region which drives the Si diffusion. Annealing in vacuum reduces the oversaturation of element-III vacancies and, hence, reduces the Si diffusion. A domination of the Si donor–element-III vacancy complex emission band was found in the spectra taken in the Si-diffused region. This gives evidence for the vacancy-assisted mechanism in the Si diffusion and in the impurity-induced disordering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351120
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  • 9
    Electronic Resource
    Electronic Resource
    Light emitting porous silicon diode based on a silicon/porous silicon heterojunction (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 6474-6482 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new structure is proposed to improve the external quantum efficiency of porous silicon (PS) light emitting diodes (LED). It is based on a heterojunction between n-type doped silicon and PS. The heterojunction is formed due to the doping selectivity of the etching process used to form PS. The improvement of the proposed LED structure with respect to usual metal/PS LED is demonstrated. This is thought to be due to a different injection mechanism for which carriers are injected directly into conduction band states. Anodic oxidation experiments show further improvements in the LED efficiency.© 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371711
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  • 10
    Electronic Resource
    Electronic Resource
    Temperature dependence of the photoluminescence of all-porous-silicon optical microcavities (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 1760-1764 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence measurements in all-porous-silicon optical microcavities (PSM) are reported over a wide temperature range. Both continuous wave and time resolved measurements have been performed. The microcavity is formed by an all porous silicon Fabry–Perot filter made by two distributed Bragg reflectors separated by a λ-thick PS cavity layer. The luminescence properties of PSM are changed with respect to those of PS: a temperature independent narrowing in the emission line shape, a different temperature dependence of the emission intensity, and a fractional shortening of the luminescence decay time over the 50–300 K temperature interval are achieved. The PSM luminescence properties are explained by the spatial redistribution of the spontaneous emission, by an effective refractive index probed by the photon mode confined in the cavity layer and by the coupling between the singlet exciton state and the photon mode confined in the cavity layer. The saturation of the absorption of the distributed Bragg reflector is also addressed. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369320
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