Gated structures have been fabricated on the InAs/AlSb/GaSb system enabling the control of the relative electron and hole carrier densities in these type II crossed band gap structures. By using insulated gates, a wide gate voltage range, with very low leakage levels, is obtained, allowing the study of these systems from electron dominated transport through to hole dominated. Associated with this transition, a change from positive to negative transconductance is observed. Studies of the quantum Hall effect show features related to both electron and hole Landau level formation with the crossover from electron to hole dominated transport found to be a function of the perpendicular magnetic field. ©1997 American Institute of Physics.