Homework_1_Solution

Homework_1_Solution - 3. Name the most common semiconductor...

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Dr. Byoung Hee You TECH 4392, MFGE 4392, and TECH 5392 Solutions: Homework#1 1. How does energy-band theory explain the difference among insulators, conductors, and semiconductors? Ans) There are three different materials based on the flow of electric current through these materials. The energy band gap explains how a material can be an insulator, conductor or semiconductor. Insulators have a large energy gap between the valence and conduction bands. It is difficult for electrons to jump the gap. Conductors have overlapping bands making the jump for electrons very easy and electricity is conducted with little required energy. Semiconductors have an energy gap but when energy is supplied to the material the electrons can be excited to across the band gap. 2. What is resistance? State the resistance formula. Ans) Resistance is the material property opposing to the current flow. It is a function of resistivity, area, length of the material, R = ρL/A.
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Dr. Byoung Hee You
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Unformatted text preview: 3. Name the most common semiconductor material and give four reasons why it is so commonly used. Ans) a. Abundance of silicon. It makes up 25% of the earths crust. b. Higher melting point (1412C) makes for a wide processing range. c. Wider temperature range of operation allows increase in application and reliability. d. Natural growth of SiO 2 allows for a chemical barrier to protect Si from external contamination. 4. What is doping? Why is doping important for semiconductor silicon? Ans) Doping is the process of adding certain elements (dopants) to pure silicon to enhance its material properties, conductivity or resistance. Arsenic, as an example, increases the conductivity by increasing the number of free electrons. This makes it n-type and is negative doping. The addition of Boron would be an example of positive (p-type) doping because it forms more holes. It is easier (requires less energy) to move electrons than it is to move holes....
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This note was uploaded on 09/21/2011 for the course MFGE 4392 taught by Professor You during the Spring '11 term at Texas State.

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Homework_1_Solution - 3. Name the most common semiconductor...

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