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As a two-dimensional (2D) material, palladium diselenide (PdSe2) has attracted extensive research attention due to its unique asymmetric crystal structure and extraordinary optoelectronic properties, showing great potential in electronic, optoelectronic, and other application fields. Thinner PdSe2exhibits semiconductor properties, while the photoresponse of the photodetectors based on this film is weaker. Although increasing the thickness of the PdSe2film can improve the photoresponse, thicker PdSe2exhibits metallic-like properties, which is not conducive to the formation of the heterojunction. In this work, a PdSe22D material with a quantum island structure is prepared by a simple thermal-assisted conversion method. A new type of photodetector with a PdSe2/n–-Si/n+-Si vertical PIN-like structure is innovatively proposed. Broad spectral absorption from 532 to 2200 nm and a high rectification ratio (106) of the device are achieved. The introduced n–-Si layer concentrates the electric field in the depletion region, thereby shortening the transit time and accelerating the separation and collection of the carriers, resulting in the enhancement of the responsivity and 3 dB frequency compared to the traditional device with a PN structure. A recorded highest 3 dB frequency of ∼25 kHz is achieved for the PdSe22D-3D PIN-like device.

Ge incorporation in thin films deposited on Ge substrates by electron-beam evaporation was investigated during dry/wet thermal annealing in ambient. The structural and chemical changes and the electrical properties of were monitored by angle-resolved X-ray photoemission spectroscopy and current-voltage characteristics. Considerable Ge incorporation as in on the Ge substrate during the deposition and annealing processes led to the formation of germanate of hafnium and the deterioration of the leakage current after thermal annealing. The oxidation degree of the incorporated increased with wet annealing time. It was indicated that Ge incorporated in came from Ge upward diffusion from the Ge substrate and the GeO evaporation from the uncovered back side of the Ge substrate.

Ge incorporation in HfO2thin films deposited on Ge substrates by electron-beam evaporation was investigated during dry/wet thermal annealing in N2ambient. The structural and chemical changes and the electrical properties of HfO2were monitored by angle-resolved X-ray photoemission spectroscopy and current–voltage characteristics. Considerable Ge incorporation as GeOxin HfO2on the Ge substrate during the deposition and annealing processes led to the formation of germanate of hafnium and the deterioration of the leakage current after thermal annealing. The oxidation degree of the incorporated GeOxincreased with wet annealing time. It was indicated that Ge incorporated in HfO2came from Ge upward diffusion from the Ge substrate and the GeO evaporation from the uncovered back side of the Ge substrate.