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  • Other Sources  (17)
  • 1
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    Extremely low nonalloyed and alloyed contact resistance using an InAs cap layer on InGaAs by molecular-beam epitaxy (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Extremely low alloyed and nonalloyed ohmic contact resistances have been formed on n-type InAs/In(0.53)Ga(0.47)As/In(0.52)Al(0.48)As structures grown on InP(Fe) by molecular-beam epitaxy. To insure the accuracy of the small contact resistances measured, an extended transmission line model was used to extrapolate contact resistances from test patterns with multiple gap spacings varying from 1 to 20 microns. For a 150-A-thick InAs layer doped to 2 x 10 to the 18th/cu cm and a 0.1-micron-thick InGaAs layer doped to 1 x 10 to the 18th/cu cm, a specific contact resistance of 2.6 x 10 to the -8th ohm-asterisk sq cm was measured for the nonalloyed contact, while a resistance less than 1.7 x 10 to the -8th ohm-asterisk sq cm is reported for the alloyed contact. Conventional Au-Ge/Ni/Au was used for the ohmic metal contact and alloying was performed at 500 C for 50 s in flowing H2. Using a thermionic field emission model, the barrier height at the InAs/InGaAs interface was calculated to be 20 meV.
    Keywords: SOLID-STATE PHYSICS
    Type: Journal of Applied Physics (ISSN 0021-8979); 64; 429-431
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  • 2
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    Ultralow threshold graded-index separate-confinement heterostructure single quantum well (Al, Ga) As lasers (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Broad area graded-index separate-confinement heterostructure single quantum well lasers grown by molecular-beam epitaxy (MBE) with threshold current density as low as 93 A/sq cm (520 microns long) have been fabricated. Buried lasers formed from similarly structured MBE material with liquid phase epitaxy regrowth had threshold currents at submilliampere levels when high reflectivity coatings were applied to the end facets. A CW threshold current of 0.55 mA was obtained for a laser with facet reflectivities of about 80 percent, a cavity length of 120 micron, and an active region stripe width of 1 micron. These devices driven directly with logic level signals have switch-on delays less than 50 ps without any current prebias. Such lasers permit fully on-off switching while at the same time obviating the need for bias monitoring and feedback control.
    Keywords: LASERS AND MASERS
    Type: Journal of Vacuum Science and Technology B (ISSN 0734-211X); 6; 689-691
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  • 3
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    Characterization of graded interface In(x)Ga(1-x)As/In(0.52)Al(0.48)As (x between 0.53 and 0.70) structures grown by molecular-beam epitaxy (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Modulation-doped In(x)Ga(1-x)As/In(0.52)Al(0.48)As/InP structures were grown by molecular-beam epitaxy with x values between 53 and 70 percent. For pseudomorphic cases, graded instead of abrupt interfaces were used. Hall mobility and persistent photoconductivity measurements as a function of temperature were used to characterize samples with different structural parameters. Consistent trends in the variation of mobilities and two-dimensional carrier concentration, n(2D), under light and dark conditions have been observed and discussed in terms of applicable scattering mechanisms. The Hall mobilities are comparable to the best results obtained to date but with significantly higher n(2D) concentration.
    Keywords: SOLID-STATE PHYSICS
    Type: Journal of Applied Physics (ISSN 0021-8979); 62; 2880-288
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  • 4
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    Contact regrowth technique for low-resistance nonalloyed contacts to the hot-electron transistor (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A novel contact regrowth technique for the formation of extremely low nonalloyed ohmic contacts is reported. The successful demonstration of this technique is reported on an InGaAs/InAlAs hot-electron transistor device. For the investigated InGaAs-based structure, the regrown contacting scheme reported includes an In(0.53)Ga(0.47)As layer, an InAs/GaAs strained-layer superlattice, and an InAs cap, all heavily doped n type with Si. A very low specific contact resistance of 1.8 x 10 to the -7th ohm sq cm to the base layer is obtained. The higher current densities achieved in the transistor characteristics are in close agreement with calculations, and a contact model is presented explaining the poor results of conventional nonalloyed contacts.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Physics Letters (ISSN 0003-6951); 53; 1738-174
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  • 5
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    Extremely low resistance nonalloyed ohmic contacts on GaAs using InAs/InGaAs and InAs/GaAs strained-layer superlattices (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Employing a structure consisting of n(+)-InAs/InGaAs and InAs/GaAs strained-layer superlattices (SLSs) grown by molecular beam epitaxy on GaAs films, nonalloyed contact resistances less than 8.5 x 10 to the -8th ohm sq cm have been obtained. Self-consistent simulations show that these extremely small nonalloyed contact resistances are due to the suppression of the depletion depth in the GaAs channel and tunneling through the SLS layer. Similar structures on InGaAs channels have led to nonalloyed specific contact resistances of about 1.5 x 10 to the -8th ohm sq cm. These results represent the smallest figures reported for these important material systems.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Physics Letters (ISSN 0003-6951); 53; 900
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  • 6
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    Growth of (111) GaAs on (111) Si using molecular-beam epitaxy (1988)
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    Publication Date: 2011-08-19
    Description: (111) GaAs layers have been grown epitaxially on (111) Si wafers, both on-axis as well as 3-deg off-axis towards the 1 -1 0 direction, using molecular-beam epitaxy. The grown layers have been characterized by scanning electron microscopy, X-ray diffraction, and transmission electron microscopy.
    Keywords: SOLID-STATE PHYSICS
    Type: Journal of Applied Physics (ISSN 0021-8979); 64; 1596-159
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  • 7
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    InGaAs/InAlAs hot-electron transistor (1986)
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    Publication Date: 2011-08-19
    Description: Using InGaAs for the base and InAlAs for the emitter and collector barriers, the first hot-electron transistor in this material system is fabricated. It is shown that 1.6 percent of the injected hot electrons can be transported ballistically through a 0.3 micron thick In(0.53)Ga(0.47)As plus 800-A-thick InAlAs barrier layer at 77 K giving rise to an average mean free path of 920 A. An energy spread of 130 MeV was observed for the ballistic electrons injected at about 700 MeV above the thermal equilibrium conditions. The value of collector barrier heights measured are in reasonable agreement with those deduced independently from thermionic emission studies in InGaAs gate, InAlAs/InGaAs capacitor structures.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Physics Letters (ISSN 0003-6951); 48; 1799-180
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  • 8
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    Characteristics of annealed p/n junctions between GaAs and Si(100) (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Electrical characteristics of a GaAs(p)/Si(n) interface were determined from capacitance-voltage, current-voltage, and secondary ion mass spectroscopy (SIMS) measurements and compared to those on GaAs(p) epitaxial layers on GaAs(n) substrates. The comparison was made between the junctions as grown, and after an anneal at 850 C for 20 min in 10 percent forming gas under an As overpressure. For the GaAs/Si junction the ideality factor changed from 2 or larger to 1.5 and the apparent intercept voltage changed from 2.5 to 1.3 V after annealing. For the GaAs homojunction, the intercept voltage increased from 1.1 to 1.3 V. In addition, the excess current in the forward and reverse bias conditions dropped drastically in the heterojunction. No movement of the metallurgical junction was discernible to within the resolution capability of SIMS. The junction properties obtained by annealing suggest an atomic restructuring of the Si(100) interface during growth or annealing. These new results raise the possibility that the GaAs/Si interface can be made into an electrically viable junction and incorporated into active devices.
    Keywords: SOLID-STATE PHYSICS
    Type: Applied Physics Letters (ISSN 0003-6951); 51; 1995-199
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  • 9
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    GaN-based micro pressure sensor for extreme environments (2005)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The linearity and reversibility in pressure response suggest that these newly investigated n-GaN/AlxGa(1-x)N/n-GaN devices are promising candidates for high-pressure sensor applications.
    Type: IEEE Sensors 2005; Oct 31, 2005 - Nov 04, 2005; Irvine, CA; United States
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  • 10
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    Calculation of the electron wave function in a graded-channel double-heterojunction modulation-doped field-effect transistor (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Three double-heterojunction modulation-doped field-effect transistor structures with different channel composition are investigated theoretically. All of these transistors have an In(x)Ga(1-x)As channel sandwiched between two doped Al(0.3)Ga(0.7)As barriers with undoped spacer layers. In one of the structures, x varies from 0 from either heterojunction to 0.15 at the center of the channel quadratically; in the other two, constant values of x of 0 and 0.15 are used. The Poisson and Schroedinger equations are solved self-consistently for the electron wave function in all three cases. The results showed that the two-dimensional electron gas (2DEG) concentration in the channel of the quadratically graded structure is higher than the x = 0 one and slightly lower than the x = 0.15 one, and the mean distance of the 2DEG is closer to the center of the channel for this transistor than the other two. These two effects have important implications on the electron mobility in the channel.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Physics Letters (ISSN 0003-6951); 55; 1223-122
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