MULTIPLE DEEP LEVELS IN METALORGANIC VAPORPHASE EPITAXY GAAS GROWN BY CONTROLLED OXYGEN INCORPORATION

Oxygen intentionally introduced into GaAs, grown through the metalorganic vapor phase epitaxy process, is shown to introduce a controlled series of deep levels. A novel, commercially available, oxygen precursor, (C2H5)2AlOC2H5, was used as the oxygen source. Capacitance measurements have revealed compensation of both donors and acceptors in these materials when using this source. The determination of the deep level structure of these films has been carried out through the use of deep level transient spectroscopy (DLTS). The DLTS investigation, carried out on GaAs p+-n homojunctions, indicates that unlike the case of bulk oxygen-doped GaAs (GaAs:O), several deep levels are introduced and directly associated with the intentional oxygen introduction. Two principal traps are found to be located at 0.95 and 0.75 eV below the conduction-band edge, with several other minor traps being observed. These intentionally introduced deep levels have been used to form highly resistive GaAs, providing an analog to the currently employed low-temperature semi-insulating nonstoichiometric GaAs grown by molecular beam epitaxy.