  Perovskite-type iridates SrIrO$_{3}$ and CaIrO$_{3}$ are a Dirac line node
semimetal protected by crystalline symmetry, providing an interesting
playground to investigate electron correlation effects on topological
semimetals. The effect of Sn doping was examined by growing
SrIr$_{1-x}$Sn$_{x}$O$_{3}$ and CaIr$_{1-x}$Sn$_{x}$O$_{3}$ thin films
epitaxially on SrTiO$_{3}$(001) substrate using pulsed laser deposition. Upon
Sn doping, the semimetallic ground state switches into an insulator. As
temperature is lowered, the resistivity, $\rho (T)$, of
SrIr$_{1-x}$Sn$_{x}$O$_{3}$ above a critical doping level ($x_{\text{c}} \sim
0.1$) shows a well-defined transition from the semimetal to a weakly
ferromagnetic insulator at $T = T_{\text{c}}$. In contrast, the $\rho (T)$ of
CaIr$_{1-x}$Sn$_{x}$O$_{3}$ with increasing $x$ shows a rapid increase of
magnitude but does not show clear signature of metal-insulator transition in
the temperature dependence. We argue that the contrasted behavior of the two
closely related iridates reflects the interplay between the effects of electron
correlation and disorder enhanced by Sn doping.
