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  • 1
    Electronic Resource
    Electronic Resource
    Formation of interface layers in GaxIn1−xAs/InP heterostructures: A re-evaluation using ultrathin quantum wells as a probe (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 1501-1510 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the metalorganic vapor phase epitaxy growth of ultrathin GaInAs/InP and GaAs/InP quantum well (QW) structures using photoluminescence (PL) spectra as a probe for interface effects. In parallel we have also studied InAsxP1−x "interface QWs'' formed by simply exposing InP to AsH3. We see a correlation between QW properties (PL peak position, effective thickness, PL half-width) and the surface phase during the growth of the QW material. For GaAs QWs grown under conditions where typically the As-excess c(4×4)/d(4×4)- or (1×2)-like (with As double layers) surface reconstructions, we find a strong red-shift of the PL peak positions. The red-shift becomes smaller the closer the growth conditions come toward the border to the (2×4) reconstruction (with only one As-termination layer). We thus conclude that the surface itself is one source for As carryover. For GaInAs QWs a boundary between an As-excess/no As-excess surface reconstruction seems to exist at higher AsH3/lower T values. Near to this border GaInAs QWs can be deposited which show PL-half-widths between 7 and 11 meV even for the range of 1–5 ML nominal thickness. The P/As replacement reaction at the lower interface is for short AsH3 interaction times (≤1 s) restricted to less than 1 ML and contributes a relatively constant amount to the effective thickness of the QW. Similarly, we show that InAsxP1−x interface QWs formed by short time interaction of InP and AsH3, originate less from a reaction into the depth of the InP, but more from a consumption of the As which is adsorbed onto the InP surface after the AsH3 treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356385
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  • 2
    Electronic Resource
    Electronic Resource
    Dislocations in mismatched layers of GaAsxP1−x in between GaP as observed by low-temperature cathodoluminescence: Part II. Grown on (111) oriented substrates (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1667-1671 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spectrally resolved low-temperature cathodoluminescence (CL) imaging has been performed on thin, 250 A(ring), mismatched layers of GaAsxP1−x in between bulk GaP. The layers were grown on (111) oriented substrates by metalorganic vapor phase epitaxy, with layers ranging from perfectly strained to totally relaxed. CL imaging has proven to be a very sensitive technique for the study of the onset of the formation of misfit dislocations and is therefore useful for determination of the critical thickness [A. Gustafsson, M.-E. Pistol, M. Gerling, L. Samuelson, M. R. Leys and H. Titze, J. Appl. Phys. 70, 1660 (1991)]. For the use of perfectly strained layers, growth on (111) oriented substrates can be of interest since the critical thickness predicted by the mechanical equilibrium theory [J. W. Matthews and A. E. Blakeslee, J. Cryst. Growth 27, 118 (1974)] is about twice that for growth on (001) oriented substrates. In this work we show that the dislocations involved in the strain relief for the growth of mismatched layers on (111) oriented substrates are of the perfect 60° type and that the experimental critical thickness agrees well with the value expected from the mechanical equilibrium theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349534
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  • 3
    Electronic Resource
    Electronic Resource
    Reflectance difference for in situ control of surface V/III ratio during epitaxial growth of GaAs (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1737-1741 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical, in situ, real time control of surface processes during epitaxy is becoming increasingly important for the understanding and control of crystal growth. Here results are presented of in situ studies of the surface V/III balance using the reflectance-difference (RD) method during vacuum chemical epitaxy of (001) GaAs from arsine and triethylgallium. We have found a relationship between the RD signal and the V/III ratio, and we demonstrate the possibility for the use of this relationship for the optimization of growth. We have, by RD, detected a sharply defined, critical V/III ratio, below which the morphology and the photoluminescence intensity deteriorate dramatically, and which can be used to control the conversion from n-type to p-type conductivity. We believe that these observations will be of great importance for the in situ optimization of epitaxial growth, and in eliminating much of the uncertainties involved in reproducing surface V/III ratios.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349513
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  • 4
    Electronic Resource
    Electronic Resource
    Dislocations in mismatched layers of GaAsxP1−x in between GaP as observed by low-temperature cathodoluminescence: Part I. Grown on (001) oriented substrates. (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1660-1666 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The possibility of growing lattice-mismatched layers and quantum wells becomes more and more interesting for the fabrication of devices. For device performance it is necessary to control the formation of misfit dislocations within the mismatched layers. It is therefore essential to study the onset of misfit dislocations versus amount of mismatch and layer thickness. A preliminary cathodoluminescence (CL) investigation, performed on layers of GaAsxP1−x mismatched to GaP barriers, was presented [A. Gustafsson, J. Jönsson, M. Gerling, M. R. Leys, M.-E. Pistol, L. Samuelson, and H. Titze, Inst. Phys. Conf. Ser. No 100, 771 (1989)]. In this paper the critical thickness with respect to the composition, x, in GaAsxP1−x, is studied from a determination of the onset of the formation of dislocations as observed in the monochromatic CL images. The experimental values of the critical thickness are compared to theoretical predictions for the critical thickness, according to different theories. The best agreement is found with the mechanical equilibrium theory, which assumes that the barrier for the formation of dislocations is negligible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349533
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  • 5
    Electronic Resource
    Electronic Resource
    Optical detection of growth oscillations in high vacuum metalorganic vapor phase epitaxy (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 2414-2416 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first measurements of growth oscillations in high vacuum metalorganic vapor phase epitaxy (MOVPE). The reflection difference response of the surface is used for real-time monitoring of the layer-by-layer growth of GaAs from triethylgallium (TEG) and arsine. The frequency of the optically detected growth oscillations is found to be proportional to the flux of TEG and to the growth rate. We expect our results to extend the more limited ranges of applicability offered by reflection high-energy electron diffraction to allow the study of growth oscillations also in other MOVPE-related growth techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102895
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  • 6
    Electronic Resource
    Electronic Resource
    Cathodoluminescence observation of extended monolayer-flat terraces at the heterointerface of GaInAs/InP single quantum wells grown by metalorganic vapor phase epitaxy (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 878-880 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High quality, GaInAs, single quantum wells lattice matched to InP barriers, have been grown by metalorganic vapor phase epitaxy at reduced pressures and with the application of short growth interruptions at both heterointerfaces. The occurrence of multiple peaks in the 25 K cathodoluminescence spectrum of a sample containing nominally two single quantum wells is caused by terraces differing by one monolayer in thickness, ≈ 2.93 A(ring), in the same quantum well. For their observation as well defined excitonic emission peaks, the terraces must be larger in lateral extent than the free exciton Bohr diameter, namely, ≈ 350 A(ring). This number sets the lower boundary of the size of the terraces. Cathodoluminescence images were formed for the individual emission peaks and the contrast fluctuations observed with a lateral extent up to ≈ 2 μm give the upper boundary for the extended monolayer-flat terraces. So far this is the first direct observation of such large growth islands at the heterointerface of the GaInAs/InP system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103393
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  • 7
    Electronic Resource
    Electronic Resource
    Nitrogen pair luminescence in GaAs (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1451-1453 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the first observation of different nitrogen pair complexes in GaAs. These complexes, which have been searched for since the '60s, are studied under the application of hydrostatic pressure. By carefully tuning the pressure, we make one after the other of the NNi pairs (1≤i≤10) appear in the band gap of GaAs and then become the major exciton recombination channel. We compare our results for nitrogen states in GaAs with the classical case of NNi excitons in GaP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102495
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  • 8
    Electronic Resource
    Electronic Resource
    Single-monolayer quantum wells of GaInAs in InP grown by metalorganic vapor phase epitaxy (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1128-1130 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaInAs/InP quantum wells differing in thickness between 1 and 20 monolayers (1 monolayer≈2.93 A(ring)) have been grown by low-pressure (50 mbar) metalorganic vapor phase epitaxy and investigated by 2 K photoluminescence. To our knowledge this is the first observation of the one monolayer quantum well. Well-resolved photoluminescence peaks were observed and were attributed to recombination of excitons bound to quantum wells of defined monolayer thickness. The growth rate could be adjusted to produce a one monolayer quantum well. Its photoluminescence peak was observed at 1.245 eV, corresponding to a quantum confinement shift of 434 meV. The full width at half maximum of this peak was only 8 meV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102589
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  • 9
    Electronic Resource
    Electronic Resource
    Cathodoluminescence of single quantum wires and vertical quantum wells grown on a submicron grating (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 695-697 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present cathodoluminescence (CL) investigations of a corrugated GaAs/AlGaAs single quantum well (QW) structure grown on a submicron grating. The CL spectra have four distinct emission peaks. Using plan-view and cross-sectional CL imaging together with cross-sectional transmission electron microscope imaging, we have assigned the four peaks: They originate in the nominal QW, a quantum wire (QWR), a vertical quantum well (VQW), and the barrier, respectively. We have CL-imaged and -characterized single QWRs and VQWs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111037
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  • 10
    Electronic Resource
    Electronic Resource
    Reevaluation of blueshifts introduced by lateral confinement in quantum-well wire structures (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 1709-1711 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The luminescence from etched quantum-well wire structures often exhibits an unexpectedly large blueshift of the peak energy position. Further, the shift is usually quite independent of the width of the wires. In this letter we show that this blueshift can be explained as a decreased transfer of excitons between areas of different monolayer thicknesses within the single quantum wells, caused by a change in the exciton diffusion from being two-dimensional in the quantum wells to one-dimensional in the wires. This reduced transfer will result in a blueshift of the peak energy position if the monolayer splitting is unresolved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109581
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