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  • 11
    Electronic Resource
    Electronic Resource
    Direct measurement of piezoelectric field in In0.23Ga0.77N/GaN multiple quantum wells by electrotransmission spectroscopy (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 531-533 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this communication, we present experimental evidence of the piezoelectric-field-induced quantum-confined Stark effect on In0.23Ga0.77N/GaN multiple quantum wells. The optical transitions in In0.23Ga0.77N/GaN p-i-n multiple quantum wells were studied by using electrotransmission (ET) at room temperature. Quantum-well-related signals are well resolved in our ET spectra. Since the strong internal electric field breaks the symmetry of the quantum wells, both the allowed and the forbidden transitions are observed. Clear energy blueshifts in accordance with increasing reversed bias are observed in ET spectra. The strength of piezoelectric field is found to be 1.7–1.9 MV/cm in the In0.23Ga0.77N strain quantum well layer, which is comparable with the measurement reported in the literature. We have shown experimentally how the piezoelectric field affects the energy shift for the strained multiple quantum wells. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1426237
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  • 12
    Electronic Resource
    Electronic Resource
    Josephson 4 K-bit cache memory design for a prototype signal processor. I. General overview (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 2371-2378 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper presents an overview of the status of a Josephson cache chip design at IBM in the Fall of 1983. Details of the design, organized as 1 K×4 bits, and employing a 2.5-μm niobium edge-junction technology, are found in the subsequent two adjoining papers. This paper presents, in a broader perspective than the adjoining papers, the background, motivation, changes from previous designs, and general difficulties of the design. General considerations related to the fabrication process and design methodology and an overview of components and the system environment are presented. A Pb-predecessor design is used as a point of reference; the discussions emphasize changes to that work. Finally, inherent design difficulties and remaining uncertainties are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335960
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  • 13
    Electronic Resource
    Electronic Resource
    Josephson 4 K-bit cache memory design for a prototype signal processor. II. Cell array and drivers (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 2379-2388 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed optimized design of a 1 K-bit memory cell array with drivers and reset gates has been carried out based upon a set of projections for achievable tolerances in linewidths, resistances, and Josephson critical currents in a 2.5-μm technology employing niobium edge junctions. The cell operating regions were significantly widened relative to a predecessor Pb-alloy design by adjusting gate and cell inductances, adjusting current levels, and by employing a different timing sequence for application of write controls. Much-improved control of array-line current oscillations, without loss of speed, was achieved by employing a distributed filtering scheme using distributed damping. The design employs trimming of currents to accommodate ±8% chip-to-chip differences in the average critical current. The cell size is 63×63 μm. Monte Carlo calculations of threshold curve tolerances and operating current sensitivities and tolerances lead to a design-limited yield of about 95% for 4 K bits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335961
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  • 14
    Electronic Resource
    Electronic Resource
    Josephson 4 K-bit cache memory design for a prototype signal processor. III. Decoding, sensing, and timing (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 2389-2399 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Designs for peripheral and timing circuits for a Josephson cache memory chip, organized as 1 K × 4-bits, are described. The designs were carried out employing a 2.5-μm minimum-linewidth niobium edge-junction technology, in conjunction with the memory cell and driver array design described in the preceding companion paper. Significant changes in decoding, sensing, and timing, relating to widening operating margins over a predecessor all-Pb-alloy design are described in detail. The resultant nominal chip access time and power are, respectively, 970 ps and 10 mW.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336303
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  • 15
    Electronic Resource
    Electronic Resource
    Performance assessment of quantum well infrared photodetectors (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1703-1705 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The performance of GaAs/AlGaAs quantum well infrared photodetectors specified in terms of background limited temperature Tb and specific detectivity D* has been calculated based on realistic detector parameters. It is found that for a detector with an external quantum efficiency η of 6.9%, Tb is 76 K for a cutoff wavelength of 10 μm. This value of Tb agrees with the recent experimental result and is significantly higher than the previous estimation given by M. A. Kinch and A. Yariv [Appl. Phys. Lett. 55, 2093 (1989)]. If η is unity, the projected Tb can be as high as 88 K with a D* of 2.2×1011 cm(square root of)Hz/W. For a lower temperature operation, D* increases to 7.5×1011 cm(square root of)Hz/W at 77 K, comparable to that of a HgCdTe detector.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112891
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  • 16
    Electronic Resource
    Electronic Resource
    Eye-diagram and scattering parameter characterization of superconducting and gold coplanar transmission lines (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2478-2480 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the gigahertz experimental results of time and frequency performance on YBCO high-temperature superconductor and gold coplanar transmission lines. An on-wafer direct probing measurement system was used to collect data at cryogenic temperatures on both YBCO and gold coplanar lines. The insertion loss of the 6 cm lines at a frequency of 2.5 GHz was measured to be −0.03 dB for the superconducting line compared to −10.4 dB for the gold line at 80 K. Eye-diagram measurements were performed on the packaged lines and show the correlation between the insertion loss of the line and the attenuation of a pseudorandom bit sequence. The measured eye height was 170 mV for the YBCO compared to 90 mV for a gold line at 1 Gbit/s and a temperature of 77 K for the packaged 6 cm lines. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112712
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  • 17
    Electronic Resource
    Electronic Resource
    Low dark current infrared hot-electron transistor for 77 K operation (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 908-910 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recently, thermal imaging using quantum well infrared photodetector (QWIP) focal plane arrays has been demonstrated. However, the operating temperature needs to be kept around 60 K due to the large dark current occurring at higher temperatures. In order to achieve thermal imaging at 77 K, we have designed and demonstrated two infrared hot-electron transistor structures, whose dark current is two to three orders of magnitude lower than that of a QWIP. The resultant dark current falls within the limit of the charge handling capacity of a readout circuit, and the infrared detection is demonstrated to be background limited at 77 K. The noise equivalent temperature difference of the detectors is estimated to be 14 and 26 mK, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109869
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  • 18
    Electronic Resource
    Electronic Resource
    Hot-electron distribution in multiple quantum well infrared photodetectors (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 2091-2093 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The hot-electron distribution in the GaAs/AlxGa1−xAs multiple quantum well structure of 10-μm infrared photodetectors is measured with a built-in energy analyzer at different temperatures. The distribution width is found to depend strongly on T in the T≈40 to 90 K range. It increases with T, reaches a maximum at around 70 K, and then decreases at higher T's. The experiment makes it possible to unambiguously identify thermally assisted tunneling as the dominant source of the dark current at 77 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110602
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  • 19
    Electronic Resource
    Electronic Resource
    Activation characteristics of a long wavelength infrared hot-electron transistor (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 442-444 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The origin of current reduction in an infrared hot-electron transistor is examined by studying the thermal activation energy of the emitter and the collector dark current as a function of emitter bias Ve. For the emitter, the activation energy Eae is found to be determined by the thermionic emission (TE) process at a small Ve. At higher Ve, Eae decreases linearly with Ve due to the increase of the thermally assisted tunneling (TAT) current enhanced by dopant migration. For the collector, the activation energy Eac is significantly higher than Eae at low biases, indicating that the collector accepts higher energy electrons injected from the emitter. For the device under study, at Ve=0.5 V, the value of Eac is the same as that of the emitter at low biases. This result shows that, up to this bias, the collector dark current consists of only the TE current but not the TAT current, thus greatly improving the detector performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112327
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  • 20
    Electronic Resource
    Electronic Resource
    Suppression of partition noise in infrared hot-electron transistors (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 238-240 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The noise properties of hot electrons in three different infrared hot-electron transistors have been characterized. We observed that there is a reduction of generation-recombination noise after the hot electrons passed through the built-in electron energy filters. The magnitude of the reduction depends on the band structure of the filters, and can be attributed to the lack of partition noise associated with the quantum transport of the hot electrons. Based on this observation, low noise infrared hot-electron transistors can be designed using appropriate filters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111515
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