The molecular orbital diagram of a doped semiconductor is shown below. If the semiconductor is silicon, does the diagram represent n-type or p-type doping and which of the following elements could be dopant? (LO 12.9)

(a) n-type, As (b) n-type, Ga (c) p-type, As (d) p-type, Ga

Video transcript

Hello everyone in this video. We're given this illustration here that shows the molecular orbital diagram of a doped semiconductor were being asked this question. Which of the following elements here could be a dope into if the semiconductor is germanium and does the diagram represent an N. Type or P type doping? So for geranium or germanium we have four valence electrons here. Important information for later. And let's go ahead and first recall some information. Alright, so we'll just go ahead and draw a blue block here. That represents our conduction band. So I'll just put an arrow here and just put conduction. Alright then we have this red box down here with a little of this blue from the conduction. And then your red is our valence bond. We see a little of the conduction going onto the valence here. And what that is. This little sliver here. That's the extra holes. All right, the same thing. Oh I forgot to label that. This is our P type. Alright, now join the end type then. Same thing using the color coordination here that I have going on. Our blue represents the conduction band. We have a little of the red going up here and that's of course are extra holes. I'll label that here. Extra holes. And then we have our valence band being fully red. Alright. And this again, let's go ahead and label that this is our N type. All right, so for our P type here. Right over here, all of our balance bonds contain our electrons and RP type is having more holes and electrons because we have more of this empty blueness. We have more blue color than our red. So let's go ahead and draw the arrow that there's more holes than electrons. And on the other hand are end type is the exact opposite. We have more electrons than holes. We see that here with more red than our blue. All right now take a look at this diagram here, matching it with these two. Then we said that more blue is going to be what we have to be R. P type because that's more holes. And another thing is that this here the semiconductor is doped with a whole energy level. So just draw a little arrow here and say that we have a P type that we see out of our answer choices that we have two different elements. That could be a dope in here which is our boron and arsenic. And they're both P types. Of course a N D r eliminate here just cross those out for us. So compared boron and arsenic, which one can fit this description and go ahead and be the dope. And so are said that you're a medium is our semiconductor. This has four valence electrons. We need something here that has less chance of electrons than our germanium. So boron has three electrons and arsenic has five valence electrons. So comparing three and 5 to 4. Of course for the lower number that's going to be three. So then are found answer is, of course answer choice B boron P type, and that's my final answer for this problem.