hw 1 solutions

# 56 10 cm 8 jb p250 diffusion current density of holes

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

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ivity 1 1.56 10 Ω ∙ cm 8 J&B P2.50 Diffusion current density of holes is The concentration profile for holes is 10 10 cm Then 10 At 0, diffusion current density is 1.2 10 A/cm 0 1.2 10 A/cm Diffusion current is 0 0∙ 1.2 10 A 7 J&B P2.52 Note that the positive direction is to the right, and the direction of the electric field is to the left, thus 20 V/cm. (The signs of , , , are very important in this exercise!) The concentration profiles are linear, thus the gradients of concentrations are ∆ ∆ 5 10 cm ∆ ∆ 5 10 cm 350 cm / V ∙ s , Mobilities of electrons and holes are From Einstein’s relationship 150 cm / V ∙ s . The diffusivities of electrons and holes are (assuming room temperature, 25.9 ) 9.1 cm /s 3.9 cm /s At 0, 10 cm , 1.01 10 cm Electron diffusion current density: 72 A/cm Hole diffusion current density: 31 A/cm Electron drift current density: 11.2 A/cm Hole drift current density: 4.85 10 A/cm Total current density: 5.4 1 m (mid-point) Since the profiles are linear, at 10 10 2 1.01 10 2 10 A/cm 5 10 10 cm 1.005 10 cm Electron and hole diffusion currents are the same as derived above: 72 A/cm 31 A/cm Electron drift current density: 5.6 A/cm Hole drift current density: 4.8 10 A/cm...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online