Question

Contrast the electron and hole drift velocities through a 10 um (micro meter) layer of intrinsic silicon across which a voltage of 5V is imposed. Let up = 480cm2/Vs and un=1350cm2/Vs.

Answer 1

Answer:

Explanation:

Since we are considering electron and hole drift velocities, then electric field E will have to be taken into consideration as well.

Where E = V/d...... 1

Drift velocity (u) = -μE. For electron.... 2

Drift velocity (v) = μE. For hole...... 3

Given that : V = 5V and d = 10 um (micro meter)

From equation 1

E = V/d

E = 5V/10×10^-4cm

E = 5V ÷1/1000

E = 5×1000

E = 5000v/cm

From equation 2

Un = -μE.

Un = - 1350cm^2/vs × 5000

= -6750000cm/s

From equation 3

Vp = μE

= 480cm^2/vs × 5000

= 2400000cm/s

Since it was stated in the question that we should contrast between hole drift and electron drift.

6750000/2400000

= 2.8125

Hence the electron drift velocity is 2.8 times that of hole drift velocity indicating that the speed of the electron through the silicon was faster.