Selenization Mechanism of Nearly 4 in. Single-Oriented PtSe₂ and PtSe₂/n^--Si/n⁺-Si 2D-3D PIN Wide-Spectrum...

PtSe₂ is notable for its high carrier mobility and exceptional air stability. Its unique thickness-dependent transition from a semiconductor to a semimetal renders it particularly promising for short-wave infrared (SWIR) detection applications. In this study, a single-crystal PtSe₂ film with an area approaching 4 in. was fabricated at low temperature under the concurrent modulation of the nonuniform gas and thermal field in a large-diameter tube. Subsequently, p-PtSe₂/n^--Si/n⁺-Si 2D-3D PIN photodetectors were constructed. The effect of the intrinsic layer thickness (0.5 versus 5 μm) on the device performance is systematically examined. Thinner devices not only deliver a wide SWIR detection range from 532 to 2200 nm but also exhibit high performance metrics, with a high rectification ratio (∼10⁶) and an ideality factor of 1.288, indicating near-ideal performance. In contrast, the thinner devices have a detectivity as high as 1.49 × 10¹¹ Jones (approximately double higher), rise and fall times as low as 24/71 μs (approximately 3-fold faster), and 3 dB cutoff frequency of 32 kHz (nearly 5-fold higher). In addition, the photodetectors display excellent imaging and polarization detection performance in the SWIR range, with a dichroic ratio reaching 36.5. This work provides significant insights for the advancement of Si-based 2D-3D integrated SWIR detectors.