quiz230B-1_2010_solution

quiz230B-1_2010_solution - +-p diode dominated by electron...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
ECE 230B Quiz-1 (Winter 2010) Assume silicon, room temperature, complete ionization. Consider an abrupt n + -p junction with p-type doping of N a = 10 17 cm -3 . (a) What is the built-in potential? (b) If both contacts are 0.1 cm away from the junction, estimate the current density at a forward bias of 0.75 V. (c) Estimate the voltage (IR) drop in the p-region due to this current. Solutions: (a) ψ bi = E g /2 q + ( kT / q )ln( N a / n i ) = 0.98 V. (b) Current of an n
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: +-p diode dominated by electron diffusion in p-type region. Electron diffusion length L n in p-type is ~ 100 μ m << contact distance W = 0.1 cm, i.e., a wide-base diode and J n = [ μ n kTn i 2 / N a L n ]exp( qV app / kT ) n ~ 1000 cm 2 /V-s, so J n ~ 1.35 A/cm 2 . (c) Resistivity of p-type, N a = 10 17 cm-3 : ρ ~ 0.2 Ω-cm. Field E = J n = 0.27 V/cm IR drop in p-region = W× E = 27 mV....
View Full Document

This note was uploaded on 10/09/2010 for the course ECE 230 at UCSD.

Ask a homework question - tutors are online