Microelectronics

Microelectronics

1. In your own words, Describe the Thomson model of the atom.
Explain, with detailed reference to key experimental work, why this model was abandoned. [10]
2. In your own words, Outline an experiment showing that electrons exhibit wave-like properties. [10]
3. In your own words, Explain the difference between intrinsic and extrinsic semiconductors, and the difference between n-type and p-type semiconductors [20]
4. In your own words, Describe with the aid of Energy Band diagrams, the effect on the silicon electrical properties of doping with
(i) donor [10] (ii) accepter [10]
5. In your own words, Explain with the aid of diagrams the behaviours of carrier concentrations and charge distributions in a semiconductor when a p-n junction is formed. [10]
6. A solid cylindrical piece of silicon has radius 2mm and length 1cm. Calculate the resistances along the length of the silicon for each of the following cases:-
(i) the silicon has a donor concentration of 5x1022m-3 [10] (ii) the silicon has an acceptor concentration of 5x1022m-3 [10] (iii) the silicon is intrinsic. [10]
[You may assume ni=1.2x1016m-3, e=0.14m2V-1s-1, h=0.048m2V-1s-1, e=1.6×10- 19C]

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