Einstein Relationship for Semiconductor

Einstein Relationship for Semiconductor
There exists a definite relationship between the mobility and diffusion coefficient of a particular type of charge carrier in the same semiconductor. The higher the value of mobility of a charge carrier, the greater will be its tendency to diffuse. The equation which relates the mobility u and the diffusion coefficient D is known as the Einstein Relationship. The Einstein relationship is expressed as
D D kT.
where D and are the diffusion coefficients expressed in cm2/s
The importance of Einstein relationship is that it can be used to determine D (or D,1), if the mobility of holes (or electrons) is measured experimentally. For an intrinsic silicon, D 13 cm/s and D,2 = 34 cm2/s. For an intrinsic germanium,D0 = 47 cm2/s and D = 99 cm2/s