  We report on the Pt doping effect on surface and electronic structure in
Ir$_{\mathrm{1-x}}$Pt$_{\mathrm{x}}$Te$_ {\mathrm{2}}$ by scanning tunneling
microscopy (STM) and spectroscopy (STS). The surface prepared by cleavage at
4.2 K shows a triangular lattice of topmost Te atoms. The compounds that
undergo structural transition have supermodulation with a fixed wave vector $q
= \frac{2\pi}{5a_m}$ (where $a_m$ is the lattice constant in the monoclinic
phase) despite the different Pt concentrations. The superconducting compounds
show patch structures. The surface of the compound that exhibits neither the
superconductivity nor the structural transition shows no superstructure. In all
doped samples, the dopant is observed as a dark spot in STM images. The
tunneling spectra near the dopant show the change in the local density of state
at approximately -200 mV. Such microscopic effects of the dopant give us the
keys for establishing a microscopic model of this material.
