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Details of Grant 

EPSRC Reference: GR/J49433/01
Principal Investigator: Kelly, Emeritus Professor MJ
Other Investigators:
Sealy, Professor B
Researcher Co-Investigators:
Project Partners:
Department: Sch of Electronics & Physical Sciences
Organisation: University of Surrey
Scheme: Standard Research (Pre-FEC)
Starts: 01 April 1994 Ends: 30 September 1997 Value (£): 219,087
EPSRC Research Topic Classifications:
Electronic Devices & Subsys.
EPSRC Industrial Sector Classifications:
Related Grants:
Panel History:  
Summary on Grant Application Form
(1) Establish ion-implantation as an alternative to mesa etching in fabricating QSDs(2) Establish selective area/depth isolation of multilayers for QSDs(3) Integrate simple QSDs(4) Establish ion-implantation as possible alternative for some QSD fabrication(5) Investigate new QSDs that rely on ion-implantationProgress:(1) Proton isolation has been used to fabricate GaAs planar-doped-barrier diodes, and the dc and rf performance of such diodes have been compared directly, both at dc and rf with mesa diodes made from the same epitaxial multilayer semiconductor material. The performance of the proton isolated diodes, even without full optimisation of the proton dose/energy parameters, already matches that achieved routinely with mesa diodes. Proton isolation is a planar process, and diodes produced with this method are more easily integrated into circuits. The possibility of using boron instead of protons is being investigated in the context of stability and lifetime. (2) The ability to proton isolate through tunnel barrier structures is being investigated in a PhD project working in parallel with this project. Initial results indicate that it still seem possible to get some resonant tunnelling in layers that have been subject to proton implantation, although with a greatly increased series resistance. (3) No progress to date, as this is contingent on success in (2) above. (4) Difficulties in growing routinely and reproducibly a precisely controlled thin layer of p+ material for a planar-doped-barrier diode suggests that ion-implantation might be revisited to place a controlled p-layer into an epitaxially grown n-i-n structure. A series of implants are being investigated with this end-goal in mind. Varactors are reverse biased p+/n junctions which are generally formed by diffusion or epitaxy. Implanted junctions are being fabricated for evaluation at rf and for comparison with diffused junctions. A lateral surface stacked varactor consisting of many lateral p-n junctions is being designed and fabricated by multiple-stripe p-implantation into a thin n+ layer grown epitaxially on semi-insulating GaAs. The cooperation of GEC-Plessey Semiconductors at Lincoln has been very helpful in the provision of material and the processing of diodes for microwave evaluation. The RA on this project is Mr S Hutchinson.
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Organisation Website: http://www.surrey.ac.uk