The influence of plasma exposure at self-bias voltages less than 200 V on electrical characteristics of Al/n-Si diodes was examined. In particular, the influence of chemical cleaning on the electrical characteristics of plasma-exposed diodes was examined. In Ar, N-2, and O-2 plasma exposure followed by postcleaning the electrical characteristics were the same as that of a nonplasma-exposed diode. The postcleaning treatment removed the damage layer formed during plasma exposure. On the other hand, in the diodes exposed to Hz and H-2-containing plasma followed by the postcleaning treatment, the electrical characteristics was not improved by the postcleaning treatment : the Schottky barrier height increased. The II-incorporated zone was not removed by the postcleaning treatment.