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  • 1
    Electronic Resource
    Electronic Resource
    Shubnikov–de Haas oscillations on as-grown and annealed molecular-beam-epitaxy-grown Hg1−xCdxTe alloys doped with indium (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 216-225 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transverse resistivity ρxx, longitudinal resistivity ρzz, and Hall resistivity ρxy on heavily indium-doped as-grown and annealed Hg1−xCdxTe (0.24〈x〈34) alloys in a magnetic field up to 12 T and temperature range 1.2–25 K have been measured. The as-grown and annealed samples show good quality Shubnikov–de Haas oscillations in which the effective masses m*, free-electron densities nSdH, and Dingle temperatures TD are extracted. The deduced m* and nSdH from the as-grown and annealed samples are in good agreement within 12%. However, there are considerable improvements in the low field Hall mobility μH (a maximum 54% increase) and a reduction in TD (a maximum 65% decline) in the annealed samples. Analysis at low field seems to indicate that broadening due to an inhomogeneous impurity distribution contributes to TD in addition to the partial cancellation produced by different frequencies of oscillations. An estimate of the average values of an electron density fluctuation Δn/n and its spatial extent ΔL based only on TD and Hall mobility temperature Tμ is presented. The deduced ΔL is in the order of mean free path l. This, therefore, can limit μH and the values of l and ΔL and this indicates that if there is an inhomogeneous distribution of indium donor, high-temperature annealing tends to homogenize the distribution of indium donors by diffusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353885
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  • 2
    Electronic Resource
    Electronic Resource
    Shubnikov–de Haas oscillations on molecular-beam-epitaxy-grown Hg1−xCdxTe alloy doped with indium (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 4326-4331 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Shubnikov–de Haas oscillations on the transverse resistivity ρxx and longitudinal resistivity ρzz of as-grown indium-doped alloys of Hg1−xCdxTe (0.24〈x〈0.34) grown by molecular-beam epitaxy on (111)B and (100) growth directions are observed in the temperature range from 1.2 to 25 K and in fields up to 12 T. The n-type density from the periodicity, the effective mass m* from the temperature dependence of the amplitude, and the Dingle temperature TD are determined from ρxx and ρzz oscillations. The oscillations establish the high Hall density which is found at low fields. The TD in ρxx is found to be higher in comparison to TD in ρzz. However, this difference decreases as the Hall density increases. The TD discrepancy is probably due to greater inhomogeneity in the plane of the layer. The TD is higher than the temperature calculated from the weak-field Hall mobility. The density and effective mass are used to calculate the energy band gap, Fermi energy, and the band-edge effective mass. The calculated energy band gaps are in good agreement with the reported results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349112
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  • 3
    Electronic Resource
    Electronic Resource
    Transmission electron microscopy study of stacking faults and the associated partial dislocations in pseudomorphic epilayers of ZnSe/GaAs(001) (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 5506-5508 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: V-shaped double triangular faults in ZnSe/GaAs epilayers have been identified to be incomplete stacking fault pyramids and single stacking faults identified as stacking fault trapezoids. It is confirmed by transmission electron microscopy that 〈101〉 open boundaries of incomplete stacking fault pyramids are 30° Shockley partial dislocations. The closely spaced parallel acute and obtuse stair-rod dislocation pair in stacking fault trapezoids form a dislocation dipole. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363482
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  • 4
    Electronic Resource
    Electronic Resource
    X-ray analysis of ZnSe/ZnSTe quantum structure (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2518-2520 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A novel microstructure of an A1BA2-type ZnSTe/ZnSe quantum structure has been investigated by high-resolution x-ray two-axis diffraction, reflectivity, and x-ray topography which offer a nondestructive, high-strain-sensitive method for analyzing low-dimensional structures. The results show that the molecular-beam-epitaxy growth condition was well controlled to suppress dislocations extending from the substrate and the epitaxial layers have high crystalline quality. The ZnS0.665Te0.335 epilayer undergoes a tensile strain with εT(parallel)=2.5633×10−2 and εT⊥=8.8254×10−2 while a compressed strain with εB(parallel)=2.7864×10−3 and εB⊥=9.5061×10−3 exists in the first layer of ZnSe. The interfacial roughness is about 5 A(ring) and the lateral correlation length ≥2000 A(ring). © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363035
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  • 5
    Electronic Resource
    Electronic Resource
    Atomic force microscopy studies of ZnSe self-organized dots fabricated on ZnS/GaP (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1340-1342 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: ZnSe self-organized dot structures on ZnS thin films were fabricated by the molecular beam epitaxy technique. In situ reflection high-energy electron diffraction studies reveal that growth interruption is required for the formation of the dot structure. Atomic force microscopy (AFM) images of the dots taken within the same day of growth reveal that the dot density increases with increasing ZnSe coverage. A density of 18 μm−2 was achieved with a coverage of 8.0 ZnSe monolayers. AFM images taken at later times (up to six months later) show ripening effects. The average dot size measured at various times after growth is consistent with the prediction of the Ostwald ripening model with a growth time constant of 4±1 days for the structure with a coverage of 8.0 ZnSe monolayers. The dot size and density in the fully ripened state are essentially independent of the initial ZnSe coverage. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122156
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  • 6
    Electronic Resource
    Electronic Resource
    Aluminum-doped n-type ZnSTe alloy grown by molecular beam epitaxy (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2519-2521 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Successful n-type doping of ZnSTe alloy using elemental aluminum source has been carried out by molecular beam epitaxy. Hall effect measurement (300–77 K) was performed on as-grown ZnS0.977Te0.023 epilayers with various dopant concentrations. Electron carrier concentration as high as 1.3×1019 cm−3 has been achieved. For carrier concentration higher than 5×1018 cm−3, the carrier concentration is independent of temperature, possibly indicating formation of a very shallow donor level. A group of ZnS1−xTex epilayers with different x values was doped using a constant aluminum beam flux for studying the dependence of the dopant activation on Te composition. Good activation of Al dopant was obtained for x value from 0 to a few percent, but it became poor for larger x value and finally Al became inactive for x values higher than 10%. Room temperature photoluminescence measurements on doped and undoped ZnS and ZnS1−xTex layers indicate that Al dopants form deep-level radiative centers in addition to a shallow donor level. The characteristics of these deep levels as a function of Te composition have also been studied. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117718
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  • 7
    Electronic Resource
    Electronic Resource
    Deep electron states in n-type Al-doped ZnS1−xTex grown by molecular beam epitaxy (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 4412-4416 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Capacitance–voltage, photoluminescence (PL), and deep level transient spectroscopy techniques were used to investigate deep electron states in n-type Al-doped ZnS1−xTex epilayers grown by molecular beam epitaxy. The integrated intensity of the PL spectra obtained from Al-doped ZnS0.977Te0.023 is lower than that of undoped ZnS0.977Te0.023, indicating that some of the Al atoms form nonradiative deep traps. Deep level transient Fourier spectroscopy (DLTFS) spectra of the Al-doped ZnS1−xTex (x=0, 0.017, 0.04, and 0.046, respectively) epilayers reveal that Al doping leads to the formation of two electron traps 0.21 and 0.39 eV below the conduction band. DLTFS results suggest that in addition to the roles of Te as a component of the alloy as well as isoelectronic centers, Te is also involved in the formation of an electron trap, whose energy level with respect to the conduction band decreases as Te composition increases. Our results show that only a small fraction of Al atoms forms nonradiative deep defects, indicating clearly that Al is indeed a very good donor impurity for ZnS1−xTex epilayers in the range of Te composition being studied in this work. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366168
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  • 8
    Electronic Resource
    Electronic Resource
    Role of the crystallographic orientation on the incorporation of indium in HgCdTe epilayers grown by molecular beam epitaxy (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 954-956 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In-doped HgCdTe films have been grown by molecular beam epitaxy (MBE) on CdTe substrates in the (100) crystallographic orientation. They were characterized by Hall and secondary-ion mass spectroscopy measurements. The results are compared with those of In-doped HgCdTe layers grown in the (111)B orientation. In the (111)B orientation indium is incorporated in the metal site whereas in the (100) orientation it appears that indium is mainly incorporated interstitially. The results agree with a Te antisite model as a possibility for explaining the electrical behavior of (100) HgCdTe grown by MBE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101734
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  • 9
    Electronic Resource
    Electronic Resource
    Observation of negative differential resistance from a single barrier heterostructure (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 54-56 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first experimental observation of negative differential resistance (NDR) due to electron tunneling in a single barrier heterostructure. The largest peak-to-valley current ratio attained is slightly greater than 2:1. The single barrier structure studied here consists of a thin CdTe layer sandwiched between two Hg0.78Cd0.22Te electrodes. In this particular material system, NDR can only be achieved at low temperatures (T=4.2 K) due to the dominance of thermionic hole currents at high temperatures. The observation of NDR in this system suggests that the low-temperature valence-band discontinuity at the HgTe-CdTe interface is small (less than 100 mV). Room-temperature operation of single barrier NDR structures may be possible in other semiconductor systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99316
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  • 10
    Electronic Resource
    Electronic Resource
    Electrical determination of the valence-band discontinuity in HgTe-CdTe heterojunctions (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 2230-2232 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Current-voltage behavior is studied experimentally in a Hg0.78Cd0.22Te-CdTe-Hg0.78Cd0.22Te heterostructure grown by molecular beam epitaxy. At temperatures above 160 K, energy-band diagrams suggest that the dominant low-bias current is thermionic hole emission across the CdTe barrier layer. This interpretation yields a direct determination of 390±75 meV for the HgTe-CdTe valence-band discontinuity at 300 K. Similar analyses of current-voltage data taken at 190–300 K suggest that the valence-band offset decreases at low temperatures in this heterojunction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98949
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