  We consider a combination of linear confining and Hulth\'en potentials in the
Hamiltonian and via the perturbation approach, report the corresponding
Isgure-Wise function parameters. Next, we investigate the Isgur-Wise Function
for $\overline{B}\longrightarrow Dl\overline{\nu}$ and
$\overline{B_{s}}\longrightarrow D_{s}l\overline{\nu}$ semileptonic decays and
report the decay width, branching ratio and $|V_{cb}|$ CKM matrix element. A
comparison with other models and experimental values is included.
