Study on the Preparation and PEC-Type Photodetection Performance of ß-Bi2O3 Thin Films.

Bismuth-based compounds have been regarded as a kind of promising material due to their narrow bandgap, high carrier mobility, low toxicity, and strong oxidation ability, showing potential applications in the field of photoelectrochemical (PEC) activities. They can be applied in sustainable energy production, seawater desalination and treatment, optical detection and communication, and other fields. As a member of the broader family of bismuth-based materials, ß-Bi2O3 exhibits significant advantages for applications in engineering, including high photoelectric response, stability in harsh environments, and excellent corrosion resistance. This paper presents the synthesis of ß-Bi2O3 thin films utilizing the mist chemical vapor deposition (CVD) method at the optimal temperature of 400 °C. Based on the ß-Bi2O3 thin film synthesized at optimal temperature, a PEC-type photodetector was constructed with the highest responsivity R of 2.84 mA/W and detectivity D of 6.01 × 1010 Jones, respectively. The photodetection performance was investigated from various points like illumination light wavelength, power density, and long-term stability. This study would broaden the horizontal and practical applications of ß-Bi2O3.

Mechanism of V-Shaped Pits on Promoting Hole Injection in the InGaN MQWs: First-Principles Investigation.

In the InGaN multiple quantum wells (MQWs), V-shaped pits play a crucial role in carrier transport, which directly affects emitting efficiency. First-principles calculations are applied to investigate the formation of the V-shaped pits, and the results indicate that they are inclined to form in the N-rich environment. Meanwhile, we calculate the interfacial electronic properties of the sidewalls of the V-shaped pits with varying indium (In) and magnesium (Mg) compositions. The calculated valence band offset (VBO) of the In0.3Ga0.7N/Ga0.94Mg0.06N (0001) is 0.498 eV, while that of the In0.07Ga0.93N/Ga0.94Mg0.06N (101̅1) is 0.340 eV. The band alignment results show that the valence band edges in the Ga1-yMgyN layer are in higher energy than in the InxGa1-xN layer. These are in good agreement with the values reported in the previous numerical simulation. Moreover, the calculation of the projected density of states (PDOS) of interfaces discloses that the strong hybridization between the N 2p orbital and the Mg 2p orbital exerts a vital influence on the upward shifts of the valence band edges in the superlattices (SLs). All these results reveal that holes are easier to inject into the quantum wells (QWs) via the sidewall of V-shaped pits rather than the c-plane QWs, providing a theoretical basis for the growth of InGaN MQWs samples containing V-shaped pits.