CONDUCTION IN NONSTOICHIOMETRIC MOLECULAR-BEAM EPITAXIAL GAAS GROWN ABOVE THE CRITICAL THICKNESS

Different conduction behavior is observed in nonstoichiometric (NS) mo lecular-beam epitaxial GaAs grown at 200 degrees C below and above the critical thickness,In the low-field Ohmic region only the monocrystal line part of the layer contributes to the room-temperature resistivity , but at higher temperatures the resistivity scales with the total lay er thickness. In NS GaAs grown above the critical thickness, a superli near J-V-n (n = 2-3) dependence is found at intermediate fields. The p rebreakdown voltage is proportional to the total thickness. This indic ates that different defects control the electrical properties of the p olycrystalline and monocrystalline parts of the NS GaAs. These results can be useful in the design of NS GaAs based devices, which operate a t higher temperature and/or higher electric fields. (C) 1998 American Institute of Physics.