Hall effect on a thin film is for investigating charge carrier property or conductivity of materials, which form the thin film. If a substrate contributes to the conducting property, it is much complicated to the results of Hall effects on a thin film. Therefore, a film had better to coat on an insulated substrate in order to study the thin film materials.
Parallel construction path or multiple conduction path refers to doping semiconductor materials on a substrate. There are many published papers available to read. Here I list two of them to explain how to do and what it is.
During the Hall effect measurement, contact mode play an important role which is basically done by stylus profilometer (limited in speed and accuracy) that measures the thickness and roughness by monitoring the deflections of a highly fine tipped cantilever called stylus, when it is dragged along the surface of the film. Stylus profilo-meter is a low cost equipment. It requires a step, i.e. a considerable change in the height of the film to measure thickness. This method is usually preferred while measuring opaque films, such as metals or insulators. Or
In one word: you should try with Insulating substrate