{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

EE 2 HW 2 09Spring-PS2-Solns

# EE 2 HW 2 09Spring-PS2-Solns - EE2 Problem Set#2 Solutions...

This preview shows pages 1–2. Sign up to view the full content.

EE2 Problem Set#2 Solutions Question #1: (5 points) Describe the difference between unipolar and bipolar conduction. Unipolar conduction involves only one type of charge carrier (electrons or holes), while bipolar conduction involves both electrons and holes. Question #2: (5 points) The density of states in the conduction band increases with the square root of energy. Why then, can we state that most of the electrons are near the band edge, E c ? The number of carriers is equal to the integral (over energy) of the density of states multiplied by the probability that the state is filled (Fermi-Dirac or Maxwell-Boltzmann statistics). The probability exponentially decreases with increasing energy, and the exponential decreases much more rapidly than the square root increases. Question #3: (15 points): (a) Show that the Fermi function is symmetric about E F , i.e., f E F + Δ E ( ) = 1 f E F − Δ E ( ) (b) Show that when E E F ( ) >> kT , f E ( ) e E E F kT .

This preview has intentionally blurred sections. Sign up to view the full version.

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

{[ snackBarMessage ]}