It depends on how you read the question.
You guys are correct with your explanations--Carbonzit and KISS suggest the overall charge, whereas Ratch gets much further into detail. Let's take a look at what the doping does.
Semiconductors are often based around silicon. A silicon atom has four valence electrons, so when they come together they form a sort of lattice as in the picture below:
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You can see that there are very few "floating" electrons (they are only found around the edges). Because there are no free electrons, it is difficult for current to flow. That is why just pure silicon is an insulator.
Doping, however, changes the number of free electrons. First, let's look at N-type. N-type doping is often done with phosphorus. Phosphorus has five valence electrons, meaning there are five electrons around the outside. When Phosphorus atoms are bonded with silicon, each one has an extra un-bonded electron, as in the picture (sorry for the size):
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Because of the "extra" electrons, which are free to "move around," it allows current to flow.
Finally, let's look at P-type doping. P-type doping is often done with boron (3 valence electrons). When bonded with silicon, they create "holes" (as carbonzit mentioned) where electrons
could be:
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As you can see, there is a "missing" electron on the right-hand side of the boron atom in the picture.
In this case, the electrons "fit into" the "holes", allowing current to flow, but in a different fashion.
When you have N-type doping, there are "extra" electrons, making the overall charge more negative (hence the 'N'). On the other hand, when you have P-type doping, there are "not enough" electrons, making the overall charge more positive ('P').
I have simplified some of the expressions here to make them easier to understand, so some may not be the scientific way to say it, but at least it is understandable
I hope this helps!
Der Strom