transistor (1 Viewer)

[CaR]

hey...does anyone have any additional information on the syllabus dotpoint about the discussion of how shortcomings in available technology lead to an increased knowledge of the properties of materials with particular reference to the invention of the transistor?

 

[+:: $i[Q]u3 ::+]

i don't remember there being a great deal of info being available =P it was basically that the telephone was a great invention, but it used thermionic devices which greatly reduced the reliabililty and so made phone calls (particularly long distance) difficult, and this unreliability was becoming intolerable. Around the same time, some scientists (dammit i've forgotten their names but u know who i'm talkin bout...) were workin with semiconductor materials, realising the output could be greater than the input. Put the two together; they figured these materials had potential in solving the telephone problem, so put more effort and research into its application and so led to the development of the modern transistor, the replacement for the original thermionic device.

 

[CaR]

hey thanks! i found some other information...today

besides germanium and silicon, were there any other semiconductor materials that were used for the improvement of communication technology?

 

[redslert]

from my notes

o Identify that the use of germanium in early transistors is related to lack of ability to produce other materials of suitable purity.
By adding selected impurities, such as Arsenic and Gallium, to semiconductors, the number of free electrons able to move relatively easily into the conduction band, is increased.
The semi conducting material used in early transistors was made as pure as possible to reliably achieve the desired properties for transistor use.
The production of semiconductor devices requires semiconductor material with almost perfect crystalline structure. Due to the interest in germanium at that time, techniques for its purification were developed and improved throughout the 1940’s. Although silicon (Si) was also known to be a semiconductor at that time, techniques for its purification were not developed until the 1950’s. For this reason germanium was the first semiconductor material used to produce semiconductor devices. Most notably germanium was used to produce the first transistors in 1948.

 

[xeriphic]

sorry to interrupt but can somone explain to me how junction transistors work, pnp and npn which gets me confused

 

[redslert]

Originally posted by xeriphic
sorry to interrupt but can somone explain to me how junction transistors work, pnp and npn which gets me confused

sorry but my memory for physics is very scratchy

i hope this is what you are searching for?

 

[kheir]

i cant be bothered explaining either but its got something to do with depletion zones where the n type swaps its electrons with the holes in the p type this forms two barriers in each side ( hypothetically speaking) a large negative wall in the p type and a positive wall in the n type. this is why electrons can only flow from n type to p type if it was the other way the electron would meat a wall of negatives hence continuosly being reppelled

 

[ashtor]

sorry but i didnt really understand that kheir,... a little elaboration perhaps?