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The dc and microwave results of Si 0 2 Ge 0 8 /Si 0 7 Ge 0 3 pMODFETs grown on silicon-on-sapphire (SOS) substrates by ultrahigh vacuum chemical vapor deposition are reported. Devices with = 0 1 m displayed high transconductance (377 mS/mm), low output conductance (25 mS/mm), and high gate-to-drain breakdown voltage (4 V). The dc current-voltage (I-V) characteristics were also nearly identical to those of control devices grown on bulk Si substrates. Microwave characterization of 0 1 50 m 2 devices yielded unity current gain ( ) and unilateral power gain ( max ) cutoff frequencies as high as 50 GHz and 116 GHz, respectively. Noise parameter characterization of 0 1 90 m 2 devices revealed minimum noise figure ( min ) of 0.6 dB at 3 GHz and 2.5 dB at 20 GHz. Index Terms-Germanium alloys, heterojunctions, MODFETs, semiconductor device noise, semiconductor epitaxial layers, silicon alloys, silicon-on-insulator technology. R ECENT advances in SiGe strained-layer modulation-doped field-effect transistor (MODFET) technology indicate that these devices may hold promise for a wide variety of future microelectronic applications, including wireless and wired communications [1], [2], as well as future advanced logic technology [3], [4]. For communications applications in particular, losses and isolation problems due to the conducting Si substrate represent a serious disadvantage compared to III-V devices that utilize semi-insulating substrates, and these problems worsen with increased frequency. The use of insulating substrates such as sapphire is a potential solution to this problem, and previous results on Si [5] and pseudomorphic SiGe-channel MOSFETs [6] fabricated on silicon-on-sapphire (SOS) wafers have produced encouraging results. However, SiGe MODFETs require relaxed SiGe buffer layers, and the growth of high-quality relaxed SiGe on sapphire or SOS substrates has not previously been demonstrated. In this paper, we present the fabrication and characterization of 0.1 m gate-length pMODFETs fabricated on high-mobility Si Ge /Si Ge quantum wells grown on SOS wafers. We show that high-mobility heterostructures can be grown on these Manuscript

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