Visible-range and self-powered bilayer p-Si/n-Bi2S3 heterojunction photodetector: The effect of Au buffer layer on the optoelectronics performance

The present research is conducted to investigate the effect of Au coating on the physical properties of the nanostructured Bi2S3 for optoelectronics applications. The Bi2S3 films are deposited using the chemical vapor deposition (CVD) at three different temperatures. The structural analysis shows the formation of polycrystalline orthorhombic Bi2S3 films and Bi-rich composition. In addition, the morphological studies indicate dense and compact films with nanorod-like morphology on the surface. Optical evolution of Bi2S3 films demonstrates an increase in the optical energy band gap (Eg) once the deposition temperature increases. Moreover, the addition of Au coating increases the absorption intensity and Eg of the samples in comparison with the Free-coated samples. The Mott-Schottky analysis indicates the highest carrier concentration amount (7.67 x10+18 cm-3) for the Aucoated samples which are deposited at 420 degrees C. The photodetector characteristics of the fabricated p-Si/n-Bi2S3 heterojunction devices show meaningful improvement in the quality parameters (QPs), including gain (G) and sensitivity (S). The charge transportation mechanism of the devices is discussed in detail calculating ideality factor (n), carrier mobility (mu), and trap-filled limited potential (VTFL).

Automated summary

This research investigates the effect of Au coating on the physical properties of nanostructured Bi2S3 for optoelectronics applications. The results show that the addition of Au coating increases the absorption intensity and optical energy band gap of the samples, leading to improved performance of the photodetector devices.