Question

what is ' to be free of their parent atoms' in semiconductors?

Answer 1

I don't understand the question can you rephrase? Why is there an apostrophe hanging around in the middle of your sentence?

Answer 2

my question is actually, what does this phrase, 'electrons to be free of their parent atoms' mean? in the context of semiconductors..

Answer 3

Ohh i understand. Look back at my other explanation on donor atoms that i answered for you. In n-type materials, remember when the electrons broke free front the donor atom? Well picture this on a grand scale, as you increase the doping more electrons will be broken free creating more current through the system. The essential "brake free from there parent atoms" or the atoms that the came from to more as charge carriers.

Answer 4

why electron brake free from donor atom? i thought they are just supplying extra electrons so that it will conduct more as there is more delocalised electrons (using chemistry terms hehe..)
hey! is it since you are supplying electrons you are really just supplying delocalised electrons -> electrical conductivity increases??

Answer 5

Yes that is true but think of it as a chemistry stand point. These atoms that you dope with like boron lets say; let us look at the structure and energy levels.

Boron has the electron orbital notation of

\[1s^22s^22p^1\]
notice that it has two filled s orbitals and one lone electron in its p orbital. This electron will stay with the boron atom even though it is being heavily shielded from the positive nucleus until something rips it away. Now when boron is introduced into the intrinsic semiconductor the electron is now in an environment that has enough energy to rip it away from boron (the parent atom) and add to the carrier concentration of the n-type material. All though it is called a donor atom it doesn't freely give it away, it just has very little energy bounding the electron to the atom making it easier to rip away from the the intrinsic atoms present in the semiconductor.