High field domain formation and current-voltage hysteresis in selectively doped GaAs/AlGaAs multiple-quantum-well structures

We have studied the sequential tunneling of electrons in selectively doped GaAs/AlGaAs tight-binding multiple-quantum-wells (MQWs) using two structures with different doping profiles, one with Si doping in the AlGaAs barriers and other, with Si doping in the GaAs wells. In both the cases, the current-voltage (I-V) measurements showed two series of current oscillations which persisted up 200 K. The I-V characteristics also showed a hysteresis effect at increasing and decreasing voltage sweep. The voltage separations between the adjacent current oscillations in the I-V characteristics of the structures with ohmic and Schottky contact metallization give a good measure of the energy difference between the excited states and the ground state in the quantum-well, with good agreement with theoretical calculations. The process of sequential electron tunneling through the MQW structures is discussed in terms of the creation and extension of high-field domains (HFDs) due to the applied bias.