  We report the successful synthesis of FeSe$_{1-x}$S$_{x}$ single crystals
with $x$ ranging from 0 to 1 via a hydrothermal method. A complete phase
diagram of FeSe$_{1-x}$S$_{x}$ has been obtained based on resistivity and
magnetization measurements. The nematicity is suppressed with increasing $x$,
and a small superconducting dome appears within the nematic phase. Outside the
nematic phase, the superconductivity is continuously suppressed and reaches a
minimum $T_c$ at $x$ = 0.45; beyond this point, $T_c$ slowly increases until
$x$ = 1. Intriguingly, an anomalous resistivity upturn with a characteristic
temperature $T^*$ in the intermediate region of $0.31 \leq x \leq 0.71$ is
observed. $T^{*}$ shows a dome-like behavior with a maximum value at $x$ =
0.45, which is opposite the evolution of $T_c$, indicating competition between
$T^*$ and superconductivity. The origin of $T^*$ is discussed in detail.
Furthermore, the normal state resistivity evolves from non-Fermi-liquid to
Fermi-liquid behavior with S doping at low temperatures, accompanied by a
reduction in electronic correlations. Our study addresses the lack of single
crystals in the high-S doping region and provides a complete phase diagram,
which will promote the study of relations among nematicity, superconductivity,
and magnetism.
