INFLUENCE OF METAL IMPURITIES ON THE SURFACE POTENTIAL OF SILICON.

The method of surface photo-emf at high injection rates was used to determine the surface potential psi //s of silicon when its surface was doped with metal impurities. The dependences of phi //s on the concentration c of the metal impurity in HF and in water, in which a silicon sample was treated, were determined. The impurities whose electrochemical potential was positive relative to silicon (Au, Ag, Pd) reduced psi //s by 0. 22-0. 32 V when silicon was subjected to a surface treatment in HF and was doped either from a solution in HF or in H//2O; this reduction was due to the formation of surface acceptor electron states not higher than 0. 3 eV above the valence band E//v and the density of these states was at least 3. 8 multiplied by 10**1**1 cm** minus **2. Smaller changes in psi //s were observed as a result of doping with Au, Ag, and Pd impurities (from H//2O) of the surface of silicon subjected to a standard etching. The impurities whose electrochemical potential was negative compared with silicon (Mn, Fe, Zn, In, Sb) altered psi //s only slightly ( similar 0. 1 V): doping from HF with impurities in concentration c approximately equals 10** minus **5-10** minus **4 g-atom/liter produced a minimum of psi //s, which was due to the creation of acceptor and donor surface electron states as a result of doping.