Current flow in a semiconductor circuit

AI Thread Summary
In a semiconductor circuit with a DC voltage source connected to intrinsic silicon, the flow of current is limited due to the lower number of free charge carriers in the silicon compared to the metal conductors. The metal's excess electrons cannot freely flow through the silicon lattice because of the energy band structure and the lack of available states for conduction in the semiconductor. When current flows through silicon, it remains electrically neutral overall, as the movement of electrons does not change the net charge. If excess electrons were to enter the silicon, it would become negatively charged, which would create an electric field that opposes further electron flow into the material. This interaction ultimately reduces the rate at which additional electrons can enter the silicon.
CoolDude420
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Homework Statement
Hi,

This isn't a homework question. Just a thought I was having while reviewing some basics.

Let's say I have a DC voltage source. I use two metal wires to connect my DC voltage source across a piece of intrinsic undoped silicon semiconductor. Everything is at room tenperature.

Now, my understanding is that the metal being a very good conductor, will have lots of free electrons that have broken away from their covalent bonds. These electrons are available for conduction and just need a voltage to start moving.

The silicon on the other hand, being a semiconductor, has some electrons at room temperature (not as much as doped silicon) but not nearly as much as the metal.

My question is, why does the silicon limit the current flow (number of electrons) that flow in the circuit. Why can't some of the excess electrons in the metal flow through the silicon lattice and to the other terminal of the battery?
Relevant Equations
N/A
N/A
 
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CoolDude420 said:
Homework Statement:: Hi,

This isn't a homework question. Just a thought I was having while reviewing some basics.

Let's say I have a DC voltage source. I use two metal wires to connect my DC voltage source across a piece of intrinsic undoped silicon semiconductor. Everything is at room tenperature.

Now, my understanding is that the metal being a very good conductor, will have lots of free electrons that have broken away from their covalent bonds. These electrons are available for conduction and just need a voltage to start moving.

The silicon on the other hand, being a semiconductor, has some electrons at room temperature (not as much as doped silicon) but not nearly as much as the metal.

My question is, why does the silicon limit the current flow (number of electrons) that flow in the circuit. Why can't some of the excess electrons in the metal flow through the silicon lattice and to the other terminal of the battery?
Relevant Equations:: N/A

N/A
Q1. When carrying a current, is the overall charge on the piece of silicon positive, negative or neutral?

Q2. If 'excess electrons' flowed into the silicon,would the silicon become positive or negative or neutral?

Q3. If the silicon became negatively charged, how would this affect the rate at which electrons enter the silicon?
 

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