E. H. Aifer
United States Naval Research Laboratory
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Featured researches published by E. H. Aifer.
Applied Physics Letters | 2006
I. Vurgaftman; E. H. Aifer; C. L. Canedy; Joseph G. Tischler; J. R. Meyer; J. H. Warner; E. M. Jackson; G. Hildebrandt; G. J. Sullivan
A new W-structured type-II superlattice photodiode design, with graded band gap in the depletion region, is shown to strongly suppress dark currents due to tunneling and generation-recombination processes. The long-wave infrared (LWIR) devices display 19%–29% quantum efficiency and substantially reduced dark currents. The median dynamic impedance-area product of 216Ωcm2 for 33 devices with 10.5μm cutoff at 78K is comparable to that for state-of-the-art HgCdTe-based photodiodes. The sidewall resistivity of ≈70kΩcm for untreated mesas is also considerably higher than previous reports for passivated or unpassivated type-II LWIR photodiodes, apparently indicating self-passivation by the graded band gap.
Applied Physics Letters | 1998
Linda J. Olafsen; E. H. Aifer; I. Vurgaftman; W. W. Bewley; C. L. Felix; Jerry R. Meyer; D. Zhang; C.-H. Lin; S. S. Pei
A 25-stage interband cascade laser with a W active region and a third hole quantum well for the suppression of leakage current has exhibited lasing in pulsed mode up to 286 K. A peak output power of 160 mW/facet and a slope efficiency of 197 mW/A per facet (1.1 photons per injected electron) were measured at 196 K. Above 200 K, the characteristic temperature was higher (T0=53 K) and the threshold current densities lower than for a previously reported W interband cascade laser without the third hole quantum well.
Applied Physics Letters | 1998
J. R. Meyer; C. L. Felix; W. W. Bewley; I. Vurgaftman; E. H. Aifer; Linda J. Olafsen; J. R. Lindle; C. A. Hoffman; M. J. Yang; Brian R. Bennett; B. V. Shanabrook; H. Lee; C.-H. Lin; S. S. Pei; R. H. Miles
Two different approaches, a photoconductive response technique and a correlation of lasing thresholds with theoretical threshold carrier concentrations have been used to determine Auger lifetimes in InAs/GaInSb quantum wells. For energy gaps corresponding to 3.1–4.8 μm, the room-temperature Auger coefficients for seven different samples are found to be nearly an order-of-magnitude lower than typical type-I results for the same wavelength. The data imply that at this temperature, the Auger rate is relatively insensitive to details of the band structure.
Nano Letters | 2010
Adam L. Friedman; Joseph L. Tedesco; P. M. Campbell; James C. Culbertson; E. H. Aifer; F. Keith Perkins; Rachael L. Myers-Ward; Jennifer K. Hite; Charles R. Eddy; Glenn G. Jernigan; D. Kurt Gaskill
We report the first observation of linear magnetoresistance (LMR) in multilayer epitaxial graphene grown on SiC. We show that multilayer epitaxial graphene exhibits large LMR from 2.2 K up to room temperature and that it can be best explained by a purely quantum mechanical model. We attribute the observation of LMR to inhomogeneities in the epitaxially grown graphene film. The large magnitude of the LMR suggests potential for novel applications in areas such as high-density data storage and magnetic sensors and actuators.
Applied Physics Letters | 2006
E. H. Aifer; Joseph G. Tischler; J. H. Warner; I. Vurgaftman; W. W. Bewley; J. R. Meyer; J. C. Kim; L. J. Whitman; C. L. Canedy; E. M. Jackson
Results are presented for an enhanced type-II W-structured superlattice (WSL) photodiode with an 11.3μm cutoff and 34% external quantum efficiency (at 8.6μm) operating at 80K. The new WSL design employs quaternary Al0.4Ga0.49In0.11Sb barrier layers to improve collection efficiency by increasing minority-carrier mobility. By fitting the quantum efficiencies of a series of p-i-n WSL photodiodes with background-doped i-region thicknesses varying from 1to4μm, the authors determine that the minority-carrier electron diffusion length is 3.5μm. The structures were grown on semitransparent n-GaSb substrates that contributed a 35%–55% gain in quantum efficiency from multiple internal reflections.
Applied Physics Letters | 1999
W. W. Bewley; C. L. Felix; I. Vurgaftman; D. W. Stokes; E. H. Aifer; Linda J. Olafsen; J. R. Meyer; M. J. Yang; B. V. Shanabrook; H. Lee; Ramon U. Martinelli; Alan R. Sugg
Optically pumped type-II W lasers emitting in the mid-infrared exhibited continuous-wave (cw) operating temperatures of 290 K at λ=3.0 μm and 210 K at λ=6.1 μm. Maximum cw output powers for 78 K were 260 mW at λ=3.1 μm and nearly 50 mW at λ=5.4 μm. These high maximum temperatures were achieved through the use of a diamond-pressure-bonding technique for heat sinking the semiconductor lasers. The thermal bond, which is accomplished through pressure alone, permits topside optical pumping through the diamond at wavelengths that would be absorbed by the substrate.
Applied Physics Letters | 1998
W. W. Bewley; C. L. Felix; E. H. Aifer; I. Vurgaftman; Linda J. Olafsen; Jerry R. Meyer; H. Lee; Ramon U. Martinelli; John C. Connolly; A.R. Sugg; Gregory H. Olsen; M. J. Yang; Brian R. Bennett; B. V. Shanabrook
We report temperature-dependent pulsed lasing performance, internal losses, and Auger coefficients for optically pumped type-II W lasers with wavelengths in the range of 3.08–4.03 μm at room temperature. All lased to at least 360 K, and produced 1.5–5 W peak power at 300 K. Internal losses at 100 K were as low as 10 cm−1, but increased to 90–360 cm−1 at 300 K. Room temperature Auger coefficients varied from 5×10−28 cm6/s at the shortest wavelength to 3×10−27 cm6/s at the longest.
Applied Physics Letters | 2005
Andrew Hood; Manijeh Razeghi; E. H. Aifer; Gail J. Brown
We demonstrate very-long-wavelength infrared type II InAs∕GaSb superlattice photodiodes with a cutoff wavelength (λc,50%) of 17μm. We observed a zero-bias, peak Johnson noise-limited detectivity of 7.63×109cmHz1∕2∕W at 77 K with a 90%–10% cutoff width of 17 meV, and quantum efficiency of 30%. Variable area diode zero-bias resistance-area product (R0A) measurements indicated that silicon dioxide passivation increased surface resistivity by nearly a factor of 5, over unpassivated photodiodes, and increased overall R0A uniformity. The bulk R0A at 77 K was found to be 0.08Ωcm2, with RA increasing more than twofold at 25 mV reverse bias.
Applied Physics Letters | 1999
Linda J. Olafsen; I. Vurgaftman; W. W. Bewley; C. L. Felix; E. H. Aifer; Jerry R. Meyer; J. R. Waterman; Whitney Mason
Strong negative luminescence is displayed by type-II InAs/GaSb superlattice diodes under reverse bias. The negative emittance at room temperature is as high as 1.5 μW/cm2 meV at 4.9 μm, and the negative efficiency at 3.5 μm is 41% of the emission from a perfect blackbody at that temperature. The main features of the data are reproduced by a detailed photodiode simulation.
Applied Physics Letters | 2001
W. W. Bewley; M. J. Jurkovic; C. L. Felix; J. R. Lindle; I. Vurgaftman; J. R. Meyer; E. H. Aifer; James E. Butler; S. P. Tobin; P. W. Norton; M. A. Hutchins
We have characterized the negative luminescent properties of photovoltaic HgCdTe detector structures with a room-temperature cutoff of 4.2 μm. Using an optical modulation method to directly measure the emittance as a function of applied bias and temperature, the blackbody signal at 295 K is found to be suppressed by a factor of 5.6. The negative luminescence efficiency of 82% and the apparent blackbody temperature change of ≈−35 K are nearly independent of heatsink temperature over the range 265–305 K.