ece2201_a08_exam1_solution_A

ece2201_a08_exam1_solution_A - becomes a positive ion when...

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1. Semiconductor Materials and the P-N Junction [20] The Figure 1.0 below shows the electrical model of a P-N Junction under zero-bias conditions (i.e. no bias voltage applied). Fill in the blanks (a) through (g) as shown: [7] Figure 1.0 g) What do the following symbols refer to? Break down each symbol and explain each part. [8] The plus sign refers to a hole in one of the covalent bonds of an acceptor (trivalent , Boron) atom within the P-type silicon crystal. A hole is free to move and behaves like a positive charge equivalent to that of an electron, but opposite in polarity. The circle with the minus sign refers to a bound acceptor (trivalent, Boron) atom which becomes a negative ion when the hole is filled by an electron. The minus sign refers to a free electron next to a donor (pentavalent, Phosphorus) atom within the N-type silicon crystal. The circle with the plus sign refers to a bound donor (pentavalent, Phosphorus) atom which
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Unformatted text preview: becomes a positive ion when the free electron moves away from it. h) Explain why a depletion region occurs around a P-N Junction under zero bias conditions? [5] Due to thermal energy, free electrons within the N-type material diffuse across the junction and occupy holes within the P-type material. This process creates a region of ions which builds up until the resulting electric field causes a drift current in the opposite direction that balances the diffusion process. Thus, a region of ions is formed which is stripped of charge carriers. a) Type of Silicon _____P-Type_______ b) Dopant Material _____Boron________ c) Means of Conduction __Holes________ d) Type of Silicon _____N-Type_______ e) Dopant Material _____Phosphorus____ f) Means of Conduction __Free Electrons___ g) Depletion Region...
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ece2201_a08_exam1_solution_A - becomes a positive ion when...

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