Polymorph engineering in two-dimensional transition metal dichalcogenides provides an effective route for tuning structure-dependent electronic properties, yet controllable phase-selective growth remains challenging because polymorph stability is highly sensitive to growth conditions. In particular, achieving reliable phase selectivity in chemical vapor deposition (CVD) without modifying precursor chemistry or introducing external perturbations remains difficult. Here, we report a temperature-dependent CVD growth strategy for phase-selective synthesis of NbSe₂ on atomically flat WSe₂ substrates. By tuning the growth temperature, rhombohedral 3R-NbSe₂ and hexagonal 2H-NbSe₂ can be selectively obtained within distinct temperature windows, with a coexistence region observed at intermediate conditions. Structural and spectroscopic characterizations reveal clear differences in morphology, stacking configuration, and vibrational properties between the two polymorphs, while atomic-resolution microscopy confirms the formation of atomically sharp and chemically abrupt interfaces. The observed temperature-dependent phase evolution suggests that surface diffusion and nucleation behavior may play important roles during growth. In addition, metallic NbSe₂ exhibits improved carrier injection as a contact electrode, highlighting its potential for device integration. This work demonstrates a feasible approach for temperature-dependent phase-selective growth in CVD-grown two-dimensional heterostructures.

Wide-bandgap semiconductors have demonstrated considerable potential for fabricating solar-blind ultraviolet (SBUV) photodetectors, which are extensively used in both civilian and military applications. Despite this promise, the limited variety of semiconductors with suitable bandgaps hampers the advancement of high-performance SBUV detectors. In this study, we synthesized CdPS₃ transparent single crystals using the chemical vapor transport (CVT) method. Density functional theory (DFT) calculations suggest that the bandgap of CdPS₃ decreases as the material’s thickness increases, a finding corroborated by subsequent absorption spectra and photoelectric response measurements. The as-prepared CdPS₃ nanosheets were employed as channels in photodetectors, demonstrating outstanding photoelectric performance in the solar-blind ultraviolet range (at 254 and 275 nm) with high responsivity (0.3 A/W), high specific detectivity (5.5 × 10⁹ Jones), rapid response speed (2.6 ms/3.4 ms), and exceptionally low dark current (2 pA). It is noteworthy that these nanosheets exhibit almost no sensitivity to 365 nm and visible light irradiation, attributable to the direct carrier transition beyond the broad bandgap in CdPS₃. Furthermore, high-quality imaging was achieved under different gate voltages using 275 nm ultraviolet light, underscoring the potential of CdPS₃ as a new material for high-performance SBUV optoelectronic detection.