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.
2. In your own words, Outline an experiment showing that electrons exhibit wave-like properties.
3. In your own words, Explain the difference between intrinsic and extrinsic semiconductors, and the difference between n-type and p-type semiconductors
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 (ii) accepter
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.
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]