Extremely high transconductance Ge/Si0.4Ge0.6p-MODFET's grown by UHV-CVD |
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Authors: | Koester SJ Hammond R Chu JO |
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Affiliation: | IBM Thomas J. Watson Res. Center, Yorktown Heights, NY; |
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Abstract: | Ge-channel modulation-doped field-effect transistors (MODFET's) with extremely high transconductance are reported. The devices were fabricated on a compressive-strained Ge/Si0.4Ge0.6 heterostructure with a Hall mobility of 1750 cm2/Vs (30,900 cm2/Vs) at room temperature (77 K). Self-aligned, T-gate p-MODFET's with Lg=0.1 μm displayed an average peak extrinsic transconductance (g(mext)) of 439 mS/mm, at a drain-to-source bias voltage (Vds) of -0.6 V, with the best device having a value of g(mext)=488 mS/mm. At 77 K, values as high as g(mext)=687 mS/mm were obtained at a bias voltage of only Vds=-0.2 V. These devices also displayed a unity current gain cutoff frequency (fT) of 42 GHz and maximum frequency of oscillation (fmax) of 86 GHz at Vds=-0.6 V and -1.0 V, respectively |
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