HW4 ChE 350 F11

# HW4 ChE 350 F11 - tabulated: [Useful relations: h e e p e n...

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ChE 350 Fall 2011 Homework 4 (Due Thursday, Nov. 3) Name:________________________ 1 1. The temperature dependence of the carrier concentration is shown below for an n-type doped semiconductor. (A) Sketch qualitatively the locations of the Fermi levels for the three different temperature regimes of “freeze out”, “extrinsic T-region” and “intrinsic”. (B) In which temperature range, will the semiconductor have the highest electrical conductivity? [Explain your answer]

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ChE 350 Fall 2011 Homework 4 (Due Thursday, Nov. 3) Name:________________________ 2 2. Below, the intrinsic electrical conductivity of a semiconductor at two temperatures is
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Unformatted text preview: tabulated: [Useful relations: h e e p e n ; kT E N n g c 2 exp ; 1 kT =26 meV at 298K]. ( a ) Determine the band gap energy (in eV) for this material. Answer: _____________________ ( b ) Estimate the electrical conductivity at 298 K. Answer:______________________ (c) In the band diagram shown below, sketch the Fermi level position for this semiconductor. ChE 350 Fall 2011 Homework 4 (Due Thursday, Nov. 3) Name:________________________ 3 3. An Si bar that is 1 m long with a cross-sectional area of 100 m 2 is doped with 10 17 cm-3 phosphorus. Find the current at 300K with 10 V applied....
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## This note was uploaded on 12/13/2011 for the course CHE 350 taught by Professor Sanchez during the Spring '08 term at University of Texas.

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HW4 ChE 350 F11 - tabulated: [Useful relations: h e e p e n...

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