4.3 25 cm²/s. is Dn =1 A constant diffusion current of electrons is estab- lished through a semiconductor material. The value of the current density is jn = -0.5 A/cm² (the minus sign indicates that the current direction is opposite to the chosen direction of the x-axis). The electron concentration at x = = 0 is n(0) = 2 x 1015 cm 3. Determine the electron concentration at x = 25 μm if the material is (a) Si (Dn = 35 cm²/s), (b) GaAs (Dn = 220 cm²/s). A