Details of Grant 

EPSRC Reference:	GR/J82034/01
Title:	SIGE/SI MONOLITHIC MICROWAVE INTEGRATED CIRUIT TECHNOLOGY
Principal Investigator:	O'Neill, Professor A
Other Investigators:
Researcher Co-Investigators:
Project Partners:	Mitel
Department:	Electrical, Electronic & Computer Eng
Organisation:	Newcastle University
Scheme:	Standard Research (Pre-FEC)
Starts:	15 June 1994	Ends:	01 January 1995	Value (£):	149,718
EPSRC Research Topic Classifications:	Electronic Devices & Subsys.
EPSRC Industrial Sector Classifications:	Electronics
Related Grants:
Panel History:
Summary on Grant Application Form
To demonstrate deep submicron MOSFETs suitable for high frequency (10 - 40 GHz) applications; to assess the potential of a Si based monolithic microwave integrated circuit (MMIC) technology; use of SiGe technology to improve high frequency FET performance leading to faster n-channel devices and/or a more balanced CMOS. Progress:Investigation of Si MOSFETs and SiGe based HMOSFETs. Several geometries have been considered using two-dimensional computer simulation using MEDICI from TMA and BLAZE from Silvaco.Strained SiGe p-channel devices: The SiGe is compressively strained between the Si substrate and Si cap layer, which gives rise to enhanced mobility due to lifting of the degeneracy of the valence bands and reduction in carrier effective mass. The type I heterostructure provides hole confinement in the SiGe.Strained Si n-channel MOSFETs: The Si is under biaxial tension when grown pseudomorphically on a relaxed SiGe alloy buffer and capped by SiGe. This allows higher electron mobility due to reduced effective mass and lifting of conduction band degeneracy. The type II heterostructure provides for electron confinement in the strained Si channel.Such device structures are being optimised using response surface methodology to establish the optimal combination of layer thicknesses and dopings to provide maximum sheet concentrations of inversion charge in the buried channel before the onset of parasitic surface inversion.The results suggest that improvements of around 50% in the cut-off frequency can be achieved by the introduction of a thin SiGe cap above a strained Si channel. The cap moves the channel from scattering centres at the SiO2 interface, improving mobility and reducing hot carrier degradation.
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