  In the sake of connecting the charge-density-wave (CDW) of TaSe$_2$ and
single-\emph{\textbf{q}} CDW-type distortion of TaTe$_2$, we present an overall
electronic phase diagram of 1\emph{T}-TaSe$_{2-x}$Te$_x$ ($0 \leq x \leq 2$).
In the experimentally prepared single crystals, the CDW is completely
suppressed as $0.5 < x < 1.5$, while superconductivity emerges as $0.2 < x <
1.2$. Theoretically, similar to 1\emph{T}-TaSe$_2$ and 1\emph{T}-TaTe$_2$, the
hypothetic 1\emph{T}-TaSeTe with ordered Se/Ta/Te stacking shows instability in
the phonon dispersion, indicating the presence of CDW in the ideally ordered
sample. The contradictory between experimental and theoretical results suggests
that the CDW is suppressed by disorder in 1\emph{T}-TaSe$_{2-x}$Te$_x$. The
formation and suppression of CDW are found to be independent with Fermi surface
nesting based on the generated electron susceptibility calculations. The
calculation of phonon linewidth suggests the strong \textbf{\emph{q}}-dependent
electron-phonon coupling induced period-lattice-distortion (PLD) should be
related to our observation: The doping can largely distort the TaX$_6$ (X = Se,
Te) octahedra, which are disorderly distributed. The resulted puckered Ta-Ta
layers are not compatible with the two-dimensional PLD. Therefore, CDW is
suppressed in 1\emph{T}-TaSe$_{2-x}$Te$_x$. Our results offer an indirect
evidence that PLD, which can be influenced by strong disorder, is the origin of
CDW in the system.
