We compared c-axis tunneling characteristics of small stacked intrinsic Jos
ephson junctions prepared on the surface of pristine, I-, and HgI2-intercal
ated Bi2Sr2CaCu2Oy (Bi2212) single crystals. Relation between the interlaye
r coupling and the in-plane gap, estimated from I-V characteristics, seems
to contradict to the interlayer pair tunneling mechanism of high-T-c superc
onductivity. (C) 2000 Elsevier Science B.V. All rights reserved.