Growth and lateral charge transport properties of thin (d = 20-30 Angs
trom) Bi films are investigated with scanning tunnelling microscopy. B
ismuth is deposited at T=140 K onto the cleaved (110) surface of an In
P-based heterostructure. Growth at low temperature is kinetically limi
ted and leads to strained, metastable overlayers. After annealing to 3
00 K the Bi surface consists of atomically fiat terraces separated by
12 Angstrom deep holes. We find that prolonged injection of a high lat
eral current promotes significant changes in surface morphology which
are attributed to a strain relaxation process mediated by electromigra
tion. Scanning tunnelling potentiometry is applied to probe the local
response of the semimetal overlayers to the injected lateral current.
The observed potential distribution provides evidence for both phonon
and defect scattering. At the position of holes and grain boundaries w
e find typically 2-4 mV high potential steps. It is argued that these
steps indeed reflect a localized increase of the film resistance and c
annot be attributed to tip-convolution artefacts.