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  • 1
    Electronic Resource
    Electronic Resource
    Uniaxial stress dependence of the properties of the DX center in n-Al0.32Ga0.68As (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1802-1806 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the emission energy, Ee, and the capture energy, Ec, and derived the thermal activation energy of the DX center, EDX, in n-Al0.32Ga0.68As as a function of uniaxial stresses along the 〈100〉 and the 〈111〉 directions. We found that the stress coefficients of EDX change sign when the band gap of Al0.32Ga0.68As changes from direct to indirect for both stress directions, and the stress coefficients of EDX in the indirect region are about same for both stress directions. These results agree with the model proposed by Chadi and Chang which assumes that the DX center is a highly localized center and disagree with the model which takes the DX center to be the effective-mass state associated with the L minima.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351186
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  • 2
    Electronic Resource
    Electronic Resource
    Unpinned GaAs Schottky barriers with an epitaxial silicon layer (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2173-2184 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present experimental results of Al/n- and Al/p-type GaAs Schottky barrier structures grown in situ by molecular-beam epitaxy with thin Si epitaxial interfacial layers. The barrier heights are measured by the I-V, thermal activation, C-V, and photoresponse methods. Barrier heights in the range of 0.3〈φbN〈1.04 eV for n-type GaAs and 0.28 〈 φbP〈1.01 eV for p-type GaAs were obtained for Si layer thicknesses between 6 and 100 A(ring). Annealing studies conducted on the samples indicate that the structures are thermally stable to temperatures up to 450 °C. These results imply that the GaAs surface Fermi level at the Si/GaAs interface is unpinned from its customary near-midgap value. A model which involves the energy-band discontinuities ΔEC and ΔEV between GaAs and Si, the thickness, and the doping of the Si layer is suggested to account for the different barrier-height values obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349456
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  • 3
    Electronic Resource
    Electronic Resource
    Uniaxial stress effects on the AlAs/GaAs double-barrier heterostructures (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 8241-8246 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the current-voltage characteristics of GaAs-AlAs-GaAs-AlAs-GaAs double-barrier heterostructures grown by molecular beam epitaxy on (100) oriented substrates under longitudinal uniaxial stress along 〈100〉 (parallel to current) direction and transverse uniaxial stress along 〈011〉 (perpendicular to current) direction at 77 K. For longitudinal stress measurement, the peak-to-valley current ratio due to Γ conduction electrons and the peak voltage (the voltage where the current peaks) decrease essentially with longitudinal stress and the negative differential resistance (NDR) disappears at a stress that depends on the dopings and dimensions of the heterostructures. However, it is surprisingly recovered at very high stress and the peak voltage reappears at a lower voltage, which is quite in contrast with the previous report for hydrostatic pressure studies. The observed shifts of the peak voltage, the decrease of the peak current, and hence the disappearance of the NDR are consistent with pressure-induced increase of the effective mass. The recovery of Γ-NDR is explained by the more rapid reduction of Xl (momentum conserving longitudinal X valleys) nonresonant current due to the increase of reflections at GaAs/AlAs interfaces under very high uniaxial stress, where there are potential wells rather than barriers for Xl current. A distinct NDR near- zero bias (∼40 mV) appears when the externally applied uniaxial stress is high enough. This has been attributed by Mendez and Chang [Surf. Sci. 229, 173 (1990)] to the resonant tunneling between two-dimensional electron gases. Our experiment shows that this tunneling is via momentum conserving longitudinal X-valleys (Xl). For transverse stress measurement, there is no evidence of this feature up to 7 kbar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347430
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  • 4
    Electronic Resource
    Electronic Resource
    Uniaxial stress dependence of the current-voltage characteristics of n-type AlAs/GaAs/AlAs tunnel diodes at 77 K (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 525-527 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Longitudinal uniaxial stress along 〈100〉 has been applied in AlAs-GaAs-AlAs resonant tunneling heterostructures grown on (100) substrates to study the current-voltage characteristics as a function of stress. We find that the nonresonant current is due to Fowler–Nordheim tunneling currents by both longitudinal and transverse X valleys (X1 and Xt). This current decreases with low stress (〈1 kbar), increases with intermediate stress and decreases with high stress (〉9 kbar) again. This is due to the increase of the Xt barrier at low stress, the decrease of the X1 barrier at intermediate stress, and the formation and the increase of X1 potential well depth at high stress. We also find a large unexplained monotonic decrease of the resonant current through the Γ valley.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347699
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  • 5
    Electronic Resource
    Electronic Resource
    Novel high mobility Ga0.51In0.49P/GaAs modulation-doped field-effect transistor structures grown using a gas source molecular beam epitaxy (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 4632-4634 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A standard Ga0.51In0.49P/GaAs modulation-doped field-effect transistor (MODFET) structure and a novel Ga0.51In0.49P/GaAs MODFET structure where the Ga0.51In0.49P spacer layer was replaced by an undoped Al0.3Ga0.7As layer were grown using a gas source molecular beam epitaxy. The Hall mobility of the novel MODFET's structures are 6600 and 36 400 cm2/V s at room temperature and 77 K, respectively, which are more than twice as high as that in the ordinary Ga0.51In0.49P/GaAs MODFETs structure. The mobility is attributed to better carrier confinement and smoother heterointerface. Furthermore, it is found that both ordinary and novel MODFET's structures have small photo-persistant conductivity effects at low temperatures and that the FETs made in these materials had no threshold voltage shift at low temperatures after illumination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350768
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  • 6
    Electronic Resource
    Electronic Resource
    Linear in-plane uniaxial stress effects on the device characteristics of AlGaAs/GaAs modulation doped field effect transistors (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 502-505 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The current voltage relationships of AlGaAs/GaAs modulation doped field effect transistors (MODFETs) were measured as a function of applied uniaxial stress. Stresses in the [110] and [11¯0] directions on MODFETs that were grown on a (001) substrate produced threshold shifts of opposite sign. Stresses in [110] and [11¯0] directions resulted in threshold voltage pressure coefficients of −15 and 64 mV/Kbar, respectively. The asymmetric shifts in the threshold voltages are attributed to piezoelectric effects. In addition, stress induced changes in the slopes of the transconductance versus gate-to-source voltage relationships were also measured. For stresses in the [110] and [11¯0] directions, the dependencies were 0.4 and −0.7 mS/(VKbar), respectively.© 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364126
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  • 7
    Electronic Resource
    Electronic Resource
    Piezoelectric effect in (001)- and (111)-oriented double-barrier resonant tunneling devices (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7770-7774 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show experimentally that current–voltage characteristics of double-barrier resonant tunneling devices (DBRTDs) can be modified by internal polarization fields due to the piezoelectric effect induced by external uniaxial stresses. Electric polarization fields, perpendicular to the interfaces, arise in DBRTDs grown on (001)-oriented substrates under uniaxial, compressive stresses parallel to the (110) or (11¯0) crystal orientations, and in DBRTDs grown on (111)B-oriented substrates under stress parallel to (111) crystal orientation. The voltages at which the resonant tunneling current peaks occur (peak voltages) are sensitive to the polarization fields induced by external stresses. The peak voltages can shift to more positive voltages or more negative voltages depending on the directions of applied stresses. We measured current–voltage characteristics of AlAs/GaAs/AlAs double-barrier resonant tunneling structures as a function of external stresses at 77 K. Uniaxial stress was applied parallel to the (110) and the (11¯0) crystal orientations for (001)-oriented DBRTDs, as well as to the (111) orientation for (111)B-oriented DBRTDs. With the substrates grounded in all the measurements, we found that the peak voltages shift to more positive voltages for (001)-oriented DBRTDs under stress along the (110) orientation and for (111)-oriented DBRTDs under the stress along (111) orientation, and to more negative voltages for (001)-oriented devices under stress along the (11¯0) orientation. The results are in agreement with our calculations published in the preceding article, which take into account the piezoelectric effect and band alignment under stress. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362382
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  • 8
    Electronic Resource
    Electronic Resource
    Resonant tunneling in (001)- and (111)-oriented III–V double-barrier heterostructures under transverse and longitudinal stresses (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7763-7769 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Calculations of the effects of external stress on the current–voltage characteristics of double-barrier (001)- and (111)-oriented resonant tunneling devices are presented. Crystal strains arising from the application of external pressure and, in pseudomorphic structures, lattice mismatch cause shifts in the conduction and valence bands of the well and barrier layers with respect to the unstrained alignment. For certain stress orientations piezoelectric effects give rise to internal electric fields parallel to the current direction. The combined piezoelectric and band-structure effects modulate the transmission resonances which control the shape of the current versus voltage characteristics of the structures. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362381
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  • 9
    Electronic Resource
    Electronic Resource
    Schottky barrier height modification on n- and p-type GaInP with thin interfacial Si (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7931-7934 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Al/n:GaInP and Al/p:GaInP Schottky diodes have been grown by molecular-beam epitaxy with and without thin (6 A(ring)) interfacial Si layers. The Schottky barrier heights were measured by C-V, I-V, and I-V-T techniques. The n- and p-type barrier heights for the samples without interfacial Si were 0.86 and 0.93 eV, respectively. Interfacial Si enhanced the n-type barrier by 0.17 eV, and reduced the p-type barrier by 0.08 eV. The sum of the n- and p-type barrier heights for the samples with the Si layer was equal to the band gap of GaInP; without Si the sum was less. By comparing this data to the Al/Si/GaAs data, GaAs-GaInP conduction- and valence-band discontinuities of 0.05 and −0.41 eV, respectively, have been inferred. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357903
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  • 10
    Electronic Resource
    Electronic Resource
    Schottky barrier height dependence on the compensation doping in the interfacial Si layer of Al/Si/n:GaAs Schottky diodes (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 371-375 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Al/Si/n:GaAs Schottky diode structures have been grown by molecular-beam epitaxy utilizing thin (100 A(ring)) Si interfacial layers. These Si layers are unintentionally very heavily n-type doped with As from the system or from the substrate. This n-type doping is intentionally compensated with p-type (Al) doping during the growth of the Si layer in an attempt to modulate the Schottky barrier height. The resultant barrier height, as determined by I-V and C-V measurements, increases with increased acceptor doping in the Si (from 0.34 eV for no Al doping to a maximum of 1.07 eV) as per Poisson's equation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357083
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