Ion Levels of Covalent Semiconductors

In the case in which ionic equilibrium is established between the siuface and the interior, the two metal ion levels, and become equal to each other and the energy level of metal ions au.di) at the surface and in the interior is given by Eqn. 3-11  

Since the concentration of kink sites ( k 10 to 10 in the molar fraction) on the metal surface is much greater than the concentration of vacant lattice sites (xy = 10 to lO in the molar fraction) in the interior, the metal ion level of a metal phase is close to the unitary level of surface metal ions a . as shown in Eqn. 3-12 and in Fig. 3-6  

Fig 3-6. Metal ion levels at the surface and in the interior of a solid metal aM. = metal ion energy  

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