High performance 0.1 μm gate-length p-type SiGe MODFET's andMOS-MODFET's |
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Authors: | Lu W. Kuliev A. Koester S.J. Wang X.-W. Chu J.O. Ma T.-P. Adesida I. |
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Affiliation: | Microelectron. Lab., Illinois Univ., Urbana, IL ; |
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Abstract: | High performance p-type modulation-doped field-effect transistors (MODFET's) and metal-oxide-semiconductor MODFET (MOS-MODFET) with 0.1 μm gate-length have been fabricated on a high hole mobility SiGe-Si heterojunction grown by ultrahigh vacuum chemical vapor deposition. The MODFET devices exhibited an extrinsic transconductance (gm) of 142 mS/mm, a unity current gain cut-off frequency (fT) of 45 GHz and a maximum oscillation frequency (fMAX) of 81 GHz, 5 nm-thick high quality jet-vapor-deposited (JVD) SiO2 was utilized as gate dielectric for the MOS-MODFET's. The devices exhibited a lower gate leakage current (1 nA/μm at Vgs=6 V) and a wider gate operating voltage swing in comparison to the MODFET's. However, due to the larger gate-to-channel distance and the existence of a parasitic surface channel, MOS-MODFET's demonstrated a smaller peak g m of 90 mS/mm, fT of 38 GHz, and fmax of 64 GHz. The threshold voltage shifted from 0.45 V for MODFET's to 1.33 V for MOS-MODFET's. A minimum noise figure (NFmin) of 1.29 dB and an associated power gain (Ga) of 12.8 dB were measured at 2 GHz for MODFET's, while the MOS-MODFET's exhibited a NF min of 0.92 dB and a Ga of 12 dB at 2 GHz. These DC, RF, and high frequency noise characteristics make SiGe/Si MODFET's and MOS-MODFET's excellent candidates for wireless communications |
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