Hall measurements on low-mobility thin films

We review the conventional measuring standard for dc Hall measurements in van der Pauw configuration with particular focus on the challenges arising from a small Hall signal compared to sizable offset voltages, which is a typical scenario for many material systems, particularly low-mobility thin films. We show that the conventional approach of using a simple field-reversal technique is often unsuited to obtain reliable results, and present an improved correction scheme to extend the accessible measurement range to mobility values well below 1 cm2/(V s). We discuss procedures to limit the impact of temperature fluctuations and long stabilization times for highly resistive materials. We further address potential sources of error due to the presence of grain boundaries in polycrystalline specimen and due to multi-carrier conduction, both of which might yield low apparent Hall mobilities significantly underestimating the actual mobility.