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High Fmax AlGaAs/GaAs HBTs with Pt/Ti/Pt/Au Base Contacts for DC to 40 GHz Broadband Amplifiers
Tohru SUGIYAMA Yasuhiko KURIYAMA Norio IIZUKA Kunio TSUDA Kouhei MORIZUKA Masao OBARA
IEICE TRANSACTIONS on Electronics
Publication Date: 1995/08/25
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Microwave and Millimeter-Wave Technology)
semiconductor materials and devices, HBT, amplifier, base metal,
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A low contact resistivity of 4.410-7 Ωcm2 for AlGaAs/GaAs HBTs was realized using Pt/Ti/Pt/Au base metal and a 81019 cm-3 highly-doped base. A high fmax of 170 GHz was achieved by reducing a base resistance. The formation of oxide-free interface between an AlGaAs graded base and Pt-based metal was demonstrated with Auger electron spectroscopy. The optimization of the growth condition conquered the rapid current-induced degradation in the highly Be-doped HBTs. An extremely wide bandwidth of 40 GHz was attained by a Darlington feeback amplifier fabricated using these high-fmax HBTs. These properties indicate that the application of AlGaAs/GaAs HBTs can be expected to extend to future ultrahigh-speed optical transmission systems.