Electron conduction in low temperature grown GaAs

Using admittance spectroscopy, we demonstrate that electron conduction in l ow temperature grown GaAs layers takes place via hopping in a partially fil led band induced by the presence of EL2 defects associated with As antisite s. We further show that electrons thermally excited into the conduction ban d percolate around insulating regions whose size and concentration correlat e reasonably well with the existing As precipitates. This percolation regim e is therefore a first evidence that As precipitates are metallic and induc e depleted regions around themselves. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.