Test: Diffusion - Electrical Engineering (EE) MCQ

J=eDdn/dx
So D=q*m/ (q*s*(1/m))
=m²/s.

J=eDdn/dx
J=1.6*10^-19*225*(10¹⁸-(7*10¹⁷))/0.1
=108A/cm².

Jp is negative for the p type of semiconductors.

From the graph between electron concentration and the distance, we can see that the direction of the electron diffusion current density is opposite to the electron flux.

Diffusion is the process of flow of particles form the region of the high concentration to a region of low concentration.

Mobility is defined as the movement of the electrons inside a semiconductor. On the other hand, velocity gradient is the ratio of velocity to distance.

J=enµE+epµE+eDdn/dx-eDdp/dx
So, temperature isn’t a part of the equation.

: D_p=V_T*μn
= (1.38*10^-23*300*400*10^-2)/ (1.6*10^-19)
= 1.035m m²/s.

 D_n=V_T*μn
= (1.38*10^-23*300*325*10^-2)/ (1.6*10^-19)
= 0.084 m²/s.