We report investigations of the heat transfer in scanning tunneling microsc
opy and scanning thermal microscopy under ultrahigh vacuum conditions. The
distance dependence of the heat transfer is found to increase significantly
for tip-sample distances smaller than several 10 nm, indicating the existe
nce of a proximity effect in heat transfer between tip and sample. Upon sca
nning the thermal probe over the sample, topographic features of the sample
can be clearly seen in the thermal image with down to 10 nm size. (C) 1999
American Vacuum Society. [S0734-2101(99)12104-3].