Classify the following semiconductors as n-type or p-type. (a) Si doped with In (b) Ge doped with Sb (c) Gray Sn doped with As

Video transcript

Hello. In this problem we are asked to indicate that the following R. N. Type or P. Type semiconductors. Semiconductors can be single elements such as silicon or germanium and they can also have impurities. The impurities determine the type of semiconductor and we have and type and P. Type semiconductors. So this begin by just considering semiconductors made of a single element. Let's use silicon as are an example. So silicon is in group four a. It has four valence electrons. And so we have this crystal structure. If we have a impurity from Group five A will have five valence electrons. And this is referred to as Penta valent. Penta standing for five Surveillance standing for the five valence electrons. So if we add a group five element such as arsenic Then it has five valence electrons. and the lattice structure can only hold four. So we will have a free electron since electrons are negatively charged. These are referred to as an type Senate connectors. And standing for negatively charged. If we go back to our example with silicon And it's four valence electrons. And if we have an impurity that is um Group three A. We will have three valence electrons and we refer to that as tri valent. So example would be boron. And so since Moron only has three valence electrons we will have a whole and this whole it was considered to be possibly charged. And so these are referred to as P type semiconductors. So T. P. Type semiconductors have in paradise that are from Group three A. And have three valence electrons. So they have one less than the pure semiconductor material like silicon and N. Type semiconductors have impurities from Group five A. They have five in its electrons. And so they have one additional electron a free electron. And these are referred to as N. Type. So if we go back to our different types of semiconductors and then we label them as N. Type and P. Type. We're looking at then where the impurity comes from fits in group three or group five A. So for the first one we have germanium dope with arsenic. Arsenic is in group five A. So it has five valence electrons. It's referred to again as Penta violence. It has one more valence electron than Germany. Um So we'll have an extra electron. So this is referred to as N. Type. The next one then we have silicon doped with boron Braun is from Group three A. It has three valence electrons. Is referred to as Tri Valent. So boron has one less electron than silicon. And so we will have a whole and this hole is considered to be positively charged. So this is referred to as a P type semiconductor. And the last one tin doped with antimony. Antimony Is a group five a. element. It has five valence electrons. So we will have an extra valence electron as compared to 10 which has four. So having an extra electron which is negatively charged. Makes this A. And type semiconductor. So the three types of semiconductors that we have our end type, those that have five valence electrons in the dough print, and the P type, which have three valence electrons with the door open. Hope this helps. Thanks for watching.