MATS 3011 Lecture Notes - Band Gap, Inta
Document Summary
Vd = muee where mue = mobility (unit = cm2/(v*s)) mue = e(tao)/m* where tao = scattering time. J = nevd = nemuee = (sigma)e conductivity (sigma) = ne(muc) Mue = mobility of electrons resistivity (ro) = 1/sigma = 1/(ne(mue)) If n or mu go up, then resistivity will go down. Dope (put inintentional purities) --> scattering for the free-moving electrons. Deform the material --> strengthen it (more dislocation density --> mobility goes down) Defect/impurities --> increases scattering events --> mobility decreases. Ne will depend on the nature of impurities/defects. Thermal scattering: when you decrease temperature (t), reduce thermal vibrations of material --> scattering decreases --> mobility incrases. Deformation of the material: more deformation --> more dislocations --> more scattering --> less mobility. Total resistivity of material can be written as follows (basically adding up all effects ): The first part of the sum is temperature dependent.
