Laser-Tuned Large Photo Hall Effect in p-Type Silicon Based on Surface States

The photo Hall effect (PHE) has attracted much attention for a long time due to its broader application in photosensitive semiconductor devices. In this paper, we show a PHE observed in p-type silicon induced by pointolite irradiation, which differs from the conventional PHE caused by a surface light source. The Hall voltage is improved by 63 times when a laser is applied at the edge of the sample, and it presents good position-sensitive properties when the laser spot moves along the middle line of the sample. An ultra-broadband spectral responsivity is observed from 405 to 980 nm at 150–300 K. The experimental result shows that the laser-induced photo Hall voltage is not the simple superposition of photo current and dark current. Interestingly, this PHE can be greatly deteriorated when the surface state is destroyed and partially replaced by a Schottky barrier via covering with a thin Ag nanofilm. We attribute this phenomenon to the surface band bending caused by charged surface states. Compared with the traditional PHE, this laser-induced, position-sensitive, large-tuned-range effect based on surface states provides a different approach to reveal the transmission properties of local unevenly distributed non-balanced carriers and can be used to design light-sensitive Hall devices.