Diffusion length ambipolar

R. Schwarz, F. Wang and M. Reissner, Fermi level dependence of the ambipolar diffusion length in amorphous silicon thin film transistors, Applied Physics Letters, 63(8), 1083-1085 (1993). 

It has already been remarked that when the hole concentration approaches the electron concentration as in a near-intrinsic semiconductor or a photo-conductive insulator, the diffusion length is no longer the minority-carrier dilfusion length Lp = ylDpXp, but rather an ambipolar or effective L. In this section we wish to show the relationship of the measured Lq to the minority-carrier diffusion length Lp in the context of a material with the photocon-ductive properties of undoped a-Si H. 

Mouschovias T. Ch. (1991) Magnetic braking, ambipolar diffusion, cloud cores, and star formation natural length scales and protostellar masses. Astrophys. J. 373, 169-186. 

Neutral species within a plasma undergo diffusive and convective transport identical to that in a gas, however, charged species have an additional restriction as a result of the conservation of charge neutrality over distances which are greater than the Debye length of the plasma (of the order of 100 pm). Therefore, in a plasma which contains an equal number of positive ions and electrons, their transport is coupled through the coulombic interactions forcing them to have an equal diffusivity called the ambipolar diffusivity, DA3). 

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