The voltage developed along the semiconductor i.e perpendicular to magnetic field and current flow be used to glow a bulb? When hall voltage develops what happens to potential drop across the semiconductor? If we apply Kirchoff"s Voltage law,what voltage should we consider as potential drop?How is law of conservation of energy working here? Yes,many questions..
In principle yes, the piece of conductor in Hall effect can be used as a source of voltage that can supply some current, because if some charges are removed from the surfaces of the conductor, other ones will be supplied to maintain the equilibrium of electric and magnetic force on the charge carriers, similarly to chemical Volta cell, where charges will be resupplied to maintain equilibrium of macroscopic electric and electromotive force inside the cell.
Of course, the current drawn should not be too high, otherwise the current distribution in the conductor will change too much and the Hall voltage will drop. The longer the conductor (in the direction of the current), the higher the Hall current that can be drawn without appreciably impacting the Hall voltage.