Single-voltage-operation pseudomorphic HEMT withlow currentdissipation for portable power applications

Lee, Jong‐Lam; Yoo, Hyung Mo; Lee, Gi Young

doi:10.1049/el:19971271

Cited by 4 publications

(1 citation statement)

References 2 publications

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“…A Au/Ge/Ni system has been widely used as the ohmic contact to AlGaAs/InGaAs PHEMTs because of its low contact resistivity. 1 There are, however, some drawbacks, 2,3 such as roughness, nonuniformity, and poor thermal stability for the Au/Ge/Ni ohmic contact to the PHEMT device.…”

Section: Introductionmentioning

confidence: 99%

Microstructural and electrical investigation of Pd/Ge/Ti/Au ohmic contact to pseudomorphic high electron mobility transistor with undoped cap layer

Kim

Lee

1998

Journal of Applied Physics

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Microstructural reactions of Pd/Ge/Ti/Au contact to AlGaAs/InGaAs pseudomorphic high electron mobility transistor with an undoped GaAs/AlGaAs cap layer have been investigated using cross-sectional transmission electron microscopy, and the results are used to interpret the electrical properties of the ohmic contact. In the as-deposited state, a quaternary phase of PdxAlGaAs containing excess Ge atoms is formed at the interface of Pd/AlGaAs and some microvoids exist at the Pd layer in the vicinity of the interface. When the ohmic metals deposited on the undoped cap layer were annealed, the lowest contact resistivity of 9.1×10−5 Ω cm2 is obtained at 380 °C. AuGa compound is formed at the PdGe/undoped-AlGaAs interface as a result of the reaction between the ohmic metal and the undoped GaAs cap. This is due to the fast in-diffusion of Au toward the undoped AlGaAs through grain boundaries of the PdGe compound. The layer structure is changed to TiO/AuGa/PdGe/AuGa(TiAs+epi-Ge)/undoped-AlGaAs. The AuGa compound enhances the creation of group III vacancies, and the in-diffused Ge atoms occupy the vacancies. Thus, a number of electrons are produced below the contact, which plays a role in reducing the contact resistivity. For the ohmic metals deposited on n-AlGaAs by removing the undoped cap layer, the annealing temperature at which the contact resistivity has the minimum value of 2.3×10−6 Ω cm2 increases to 460 °C. The Au2Al is additionally observed at the PdGe/n-AlGaAs interface. Consequently, the layer structure is changed to TiO/AuGa/PdGe/AuGa+Au2Al(TiAs+epi-Ge)/n-type AlGaAs. The formation of Au2Al at the PdGe/n-AlGaAs interface creates more group III vacancies. Thus, the contact resistivity is further reduced by the incorporation of the in-diffused Ge into the group III vacancies. The InGaAs channel layer is observed to be intermixed in the annealed sample. This evidences the production of a large number of the group III vacancies via electrons below the contact.

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Section: Introductionmentioning

confidence: 99%

Microstructural and electrical investigation of Pd/Ge/Ti/Au ohmic contact to pseudomorphic high electron mobility transistor with undoped cap layer

Kim

Lee

1998

Journal of Applied Physics

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Single‐voltage‐supply operation of Ga_0.51In_0.49P/AlGaAS/IN_0.15Ga_0.85As PHEMTS with high‐power density

Pan

2003

Micro & Optical Tech Letters

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A Ga0.51In0.49P/AlGaAs/In0.15Ga0.85As PHEMT with the highest power density among all single‐voltage‐supply operated devices, to our knowledge, was demonstrated for the first time. Operating at 1.8‐GHz under class‐A bias conditions, this FET shows 18.84‐dBm (382.8 mW/mm) saturated power and 17.25‐dBm (265.4 mW/mm) P1dB when the drain voltage is 3.6 V. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 196–199, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11167

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Comparative investigation of MBE and MOCVD PMHEMT structures for high frequency applications

Lagadas

Michelakis

Kayambaki

et al. 1999

Materials Science and Engineering: B

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Single-voltage-operation pseudomorphic HEMT withlow currentdissipation for portable power applications

Cited by 4 publications

References 2 publications

Microstructural and electrical investigation of Pd/Ge/Ti/Au ohmic contact to pseudomorphic high electron mobility transistor with undoped cap layer

Microstructural and electrical investigation of Pd/Ge/Ti/Au ohmic contact to pseudomorphic high electron mobility transistor with undoped cap layer

Single‐voltage‐supply operation of Ga_0.51In_0.49P/AlGaAS/IN_0.15Ga_0.85As PHEMTS with high‐power density

Comparative investigation of MBE and MOCVD PMHEMT structures for high frequency applications

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Single-voltage-operation pseudomorphic HEMT withlow currentdissipation for portable power applications

Cited by 4 publications

References 2 publications

Microstructural and electrical investigation of Pd/Ge/Ti/Au ohmic contact to pseudomorphic high electron mobility transistor with undoped cap layer

Microstructural and electrical investigation of Pd/Ge/Ti/Au ohmic contact to pseudomorphic high electron mobility transistor with undoped cap layer

Single‐voltage‐supply operation of Ga0.51In0.49P/AlGaAS/IN0.15Ga0.85As PHEMTS with high‐power density

Comparative investigation of MBE and MOCVD PMHEMT structures for high frequency applications

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Single‐voltage‐supply operation of Ga_0.51In_0.49P/AlGaAS/IN_0.15Ga_0.85As PHEMTS with high‐power density