Photo-induced Hall effect in metals

Abstract

The Hall effect in metals is too small to have practical applications. Instead, the same effect in semiconductors is the standard for magnetic field sensing. Yet, in semiconducting Hall-sensors, Joule heating severely compromises the linearity range. We here show that a Hall effect can be photo-induced in metals used for bias-free magnetic sensing. The system consists of a transparent metal that forms a Schottky contact to a semiconductor. Light reaching the interface results in the injection of charge from the space charge region. If a magnetic field is applied, a transverse, open-circuit voltage appears at the metal edges that is proportional to the field, as well as light intensity. The system shows sensitivities that are comparable to semiconducting Hall-sensors but no net current flows, therefore its performances are not affected by Joule heating.

A Multilayer‐Graphene/Silicon Infrared Schottky Photo‐Diode

“…Photo-induced Hall effect measurements [28] are also exploited to support the thesis that the peak in the absorption spectrum is shifted towards longer wavelengths, due to the interaction between the MLG film and the intrinsic silicon. A thorough characterization of films grown with different deposition times on α-Al 2 O 3 (sapphire) substrates is first presented.…”

“…Finally, the optoelectronic characterization of the device is addressed. Photo‐induced Hall effect measurements are also exploited to support the thesis that the peak in the absorption spectrum is shifted towards longer wavelengths, due to the interaction between the MLG film and the intrinsic silicon.…”

“…Also, it is worth highlighting here that, since the aluminum work function (4.2 eV) is lower than that of silicon (4.6 eV), the rectifying behavior is not due to the electric contacts, which make pure ohmic junctions with the semiconductive substrate …”

“…[28,35] Current-voltage characteristics in dark, in the full spectrum of a Halogen lamp (labeled as "light") and in infrared light were measured and are shown in Figure 5b. [28,35] Current-voltage characteristics in dark, in the full spectrum of a Halogen lamp (labeled as "light") and in infrared light were measured and are shown in Figure 5b.…”

“…The working principle, usually referred to as photo-induced Hall effect, [28] is briefly explained in Figure 7. In the former case, uniform light is shed on the device and a magnetic field is applied in the plane.…”