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  • 1
    Electronic Resource
    Electronic Resource
    Highly stable W/p-In0.53Ga0.47As ohmic contacts formed by rapid thermal processing (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2220-2222 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Tungsten contacts to Zn-doped In0.53Ga0.47As have been formed by rapid thermal processing. Contacts to layers with a Zn doping concentration of 5×1018 cm−3 were rectifying as sputter deposited as well as after heat treatments at temperatures lower than 450 °C. Higher processing temperatures caused a linear decrease of the contact resistivity values from 0.6 as deposited to 0.15 Ω mm after heating at 550 °C. Rapid thermal processing at these higher temperatures stimulated the Schottky-to-ohmic contact conversion with a minimum contact resistance value of 8.5×10−5 Ω cm2 and a sheet resistance value of 150 Ω/(D'Alembertian) as a result of heating at 600 °C for 30 s. By increasing the p-InGaAs doping level to 1×1019 cm−3, the specific resistance of this contact was dropped to the minimum of 7.5×10−6 Ω cm2 as a result of heating at 600 °C for 30 s. The W/p-In0.53Ga0.47As contact showed excellent thermal stability over the temperature range of 300–750 °C, with an abrupt and almost unreacted metal-semiconductor interface. Heating at temperatures of 800 °C or higher caused degradation of the contact. This was reflected by a distinct increase in the heterostructure sheet resistance as a result of the intensive interfacial reaction which took place at the contact, accompanied by outdiffusion of both In and As.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102066
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  • 2
    Electronic Resource
    Electronic Resource
    Microstructure and contact resistance temperature dependence of Pt/Ti ohmic contact to Zn-doped GaAs (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 4133-4140 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ohmic contacts to p-GaAs, Zn doped at 5×1018 and 1×1019 cm−3, with the best specific contact resistance of 1.2×10−5 and 2.4×10−6 Ω cm2, respectively, have been formed with deposited layers of Ti and Pt. These layers, which were sequentially evaporated and then rapid thermally processed at 450 °C for 30 s, contained an interfacial layer constituted mainly of the TiAs phase adjacent to the substrate and the TixGa1−x solid solution in between it and the Ti layer. In addition, a significant amount of the Pt3Ti intermetallic was found at the Ti/Pt interface. The same metallization scheme, applied to 1×1018 cm−3 Zn-doped GaAs, produced a Schottky contact for the as-deposited and heat-treated samples. The temperature dependence characteristic of the specific contact resistance of the as-deposited Pt/Ti contacts to 5×1018 and 1×1019 cm−3 Zn-doped GaAs revealed a thermionic emission dominated carrier transport mechanism with an apparent barrier height of about 0.118 and 0.115 eV, respectively. This mechanism remained as the dominated one for the heat-treated contacts to the lower doped substrate. The contact resistance of the heat-treated contacts to the more heavily doped substrate, however, revealed a weaker temperature dependence. This indicates a conversion to a mixture of thermionic and field-emission carrier transport mechanisms across the interfacial barrier, and a reduced barrier height to a minimum value of 0.068 eV measured after sintering at 450 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346255
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  • 3
    Electronic Resource
    Electronic Resource
    Ohmic contacts to heavily carbon-doped p-AlxGa1−xAs (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2276-2279 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two different metallization schemes, AuBe(80 nm) and Pt(75 nm)/Ti(50 nm), were investigated as potential ohmic contacts for highly carbon-doped p-AlxGa1−xAs. The best contact resistance values of 0.015 and 0.025 Ω mm were achieved by applying the Pt/Ti scheme onto 1×1020 and 1×1019 cm−3 C-doped AlGaAs, respectively, followed by rapid thermal processing at 450 °C. The AuBe contacts yielded their lowest values of 0.025 and 0.05 Ω mm for the same doping levels as a result of rapid thermal processing at 425 °C. The heat treatment at 450 °C caused only limited reactions in both the Pt/Ti and Ti/AlGaAs interfaces and did not lead to significant degradation of the stable microstructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348707
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  • 4
    Electronic Resource
    Electronic Resource
    Pt/Ti/n-InP nonalloyed ohmic contacts formed by rapid thermal processing (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 3872-3875 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low resistance nonalloyed ohmic contacts of e-gun evaporated Pt/Ti to S doped n-InP 5×1017, 1×1018, and 5×1018 cm−3 have been fabricated by rapid thermal processing. The contacts to the lower doped substrates (5×1017 and 1×1018 cm−3) were rectifying as-deposited as well as after heat treatment at temperatures lower than 350 °C. Higher processing temperatures stimulated the Schottky to ohmic contact conversion with minimum specific contact resistance of 1.5×10−5 and 5×10−6 Ω cm2, respectively, as a result of rapid thermal processing at 450 °C for 30 s. Heating at a temperature of 550 °C again yielded a Schottky contact. The contact to the 5×1018 cm−3 InP was ohmic as deposited with a specific contact resistance value of 1.1×10−4 Ω cm2. Supplying heat treatment to the contact caused a decrease of the specific contact resistance to a minimum of 8×10−7 Ω cm2 as a result of rapid thermal processing at 450 °C for 30 s. In all cases, this heat treatment caused a limited interfacial reactions between the Ti and the InP, and resulted in an almost abrupt interface. Heating at temperatures higher than 500 °C resulted in an interfacial intermixing and a mutual migration and reaction of the Ti and the semiconductor elements. The Pt/Ti bilayer structure was highly tensile as deposited (5×109 dyn cm−2) and became stress-free as a result of the interfacial reactions which took place while heating the samples to temperature of 400 °C or higher.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344986
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanically and thermally stable Si-Ge films and heterojunction bipolar transistors grown by rapid thermal chemical vapor deposition at 900 °C (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 745-751 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Traditional techniques for growing Si-Ge layers have centered around low-temperature growth methods such as molecular-beam epitaxy and ultrahigh vacuum chemical vapor deposition in order to achieve strain metastability and good growth control. Recognizing that metastable films are probably undesirable in state-of-the-art devices on the basis of reliability considerations, and that in general, crystal perfection increases with increasing deposition temperatures, we have grown mechanically stable Si-Ge films (i.e., films whose composition and thickness places them on or below the Matthews–Blakeslee mechanical equilibrium curve) at 900 °C by rapid thermal chemical vapor deposition. Although this limits the thickness and the Ge composition range, such films are exactly those required for high-speed heterojunction bipolar transistors and Si/Si-Ge superlattices, for example. The 900 °C films contain three orders of magnitude less oxygen than their limited reaction processing counterparts grown at 625 °C. The films are thermally stable as well, and do not interdiffuse more than about 20 A(ring) after 950 °C for 20 min. Therefore, they can be processed with standard Si techniques. At 900 °C, the films exhibit growth rates of about 15–20 A(ring)/s. We have also demonstrated the growth of graded layers of Si-Ge, and have determined that a strain gradient exists in these layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347360
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  • 6
    Electronic Resource
    Electronic Resource
    Temperature dependence of the resistance in the Pt/Ti nonalloyed ohmic contacts to p-InAs induced by rapid thermal processing (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 4141-4150 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temperature dependence of the resistance in the Pt(60 nm)/Ti(50 nm) nonalloyed ohmic contacts to p-InAs (Zn doped 1×1018 to 1×1019 cm−3 ) induced by rapid thermal processing in the temperature range of 300–600 °C was studied. The ohmic nature of these contacts was attributed to both the low metal-semiconductor interfacial barriers and to the heavily doped semiconductor contacting layers. A phenomenological model was used to fit the measured temperature dependence contact resistance. The results indicated conversion from thermionic emission as the dominant carriers transport mechanism across the interfacial barrier for the as-deposited sample to a combination of thermionic and field emission mechanism for the heat-treated samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346256
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  • 7
    Electronic Resource
    Electronic Resource
    Au/Pt/Ti contacts to p-In0.53Ga0.47As and n-InP layers formed by a single metallization common step and rapid thermal processing (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 1123-1128 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have demonstrated the viability of depositing a thick Au bonding pad on top of Pt/Ti contacts on both p-InGaAs and n-InP within a single evaporation prior to heat treatment. This eliminates the usual post-sinter Au plating process. In particular, Au (500 nm)/Pt (60 nm)/Ti (50 nm) common contacts to Zn-doped 5×1018 cm−3 p-In0.53Ga0.47As and S-doped 1×1018 cm−3 n-InP were formed within a single pumpdown electron-gun evaporation and subsequently a single sintering process by means of rapid thermal processing. The lowest resistivity of these ohmic contacts were found to be 0.11 and 0.13 Ω mm (5.5×10−7 and 8×10−6 Ω cm2) for the p and n contacts, respectively. These values were achieved as a result of heating at 450 °C for 30 sec. This heat treatment caused a limited reaction at the Au-Pt and Pt-Ti interfaces, which did not lead to any significant intermixing of the Ti and Au. Thus, no significant indiffusion of the Au thorough the Pt barrier was observed and contact degradation did not occur. The stress of the as-deposited trilayer structure on InP was found to be 3×108 dyne cm2 tensile and increased to about 2×109 dyn cm2 as a result of the rapid thermal processing at 450 °C
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346706
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  • 8
    Electronic Resource
    Electronic Resource
    Electrical characterization of an ultrahigh concentration boron delta-doping layer (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 737-739 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a boron δ-doping layer in crystalline silicon with an electrically active concentration of 1×1022 cm−3 and a mobility of ∼20 cm2/V s. This structure was fabricated by low-temperature molecular-beam epitaxy with boron confined to 3 monolayers in the silicon growth direction. Complete electrical activation is observed, showing metallic conduction down to 4 K. This two-dimensional doped layer, incorporated into the crystal lattice, represents a volume concentration exceeding the solid solubility of boron in silicon by two orders of magnitude. These high-concentration structures fill an unexplored region of the mobility versus concentration curve.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112215
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  • 9
    Electronic Resource
    Electronic Resource
    Quantitative analysis of strain relaxation in GexSi1−x/Si(110) heterostructures and an accurate determination of stacking fault energy in GexSi1−x alloys (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 2802-2804 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a quantitative theoretical and experimental analysis of strain relaxation in GexSi1−x/Si(110) heterostructures. It is shown that above a critical composition, the critical thickness for edge a/6〈112〉 Shockley partial dislocations is less than that for 60° a/2〈110〉 total dislocations. The net (excess) stress is greater on the edge a/6〈112〉 dislocations for epilayer thicknesses, h〈hx, but greater on the 60° a/2〈110〉 dislocations for h(approximately-greater-than)hx. The sensitive calculated dependence of hx upon the stacking fault energy per unit area γ allows an experimental determination of γ=65±10 mJ m−2 for x∼0.3 in GexSi1−x.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108068
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  • 10
    Electronic Resource
    Electronic Resource
    Low-temperature homoepitaxy on Si(111) (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 204-206 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have compared ion channeling results with molecular dynamics simulations to investigate low-temperature molecular beam homoepitaxy on silicon. We report the temperature dependence, rate dependence, and thickness dependence of films grown on Si(111). For 350 A(ring) films, a transition to good crystalline quality is seen in ion channeling at growth temperatures of ≈400 °C; this is compared to ≈100 °C for (100) epitaxy. The evolution of surface microstructure leading to breakdown of epitaxial growth at low temperatures is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105966
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