Ajaz Ul Haq Hall measurements typically use a thin film on a non-conductive substrate(glass or Si/SiO2), typically 100-500 nm thick. You can achieve this by drop casting a concentrated dispersion of the nanocomposite onto the substrate and drying/annealing it.

Hall Effect measurements are often used to investigate the behaviour of charge carriers in a material, particularly in semiconductors. To perform Hall Effect measurements, samples must be prepared in a way that allows for accurate and reliable measurements. The general steps are:Material Selection - Design the sample with a specific geometry -Sample Cleaning- Mounting (Mount the sample securely in the measurement setup) - Attach contacts to the sample for measuring voltage and current- Apply a magnetic field perpendicular to both the current and voltage paths-Temperature Control(If temperature affects the properties of the material, control the sample temperature during the measurements).....

If you follow the Vander pauw method. you should make the sample square size. And the contacts should be as small as possible at the corner of the sample I mean edge of the sample. Depending on the IV curve of different contacts you should apply a minimum amount of current cause excessive current cant produce additional voltage around the contact. Calculate the contact resistance as well which should be subtracted.