Reduced silicon donor incorporation in MBE grown GaAs layers using cracker-generated dimer arsenic

Abstract

Si dopant incorporation in GaAs layers is shown to be reduced when dimer arsenic is used. Si doped GaAs layers grown by molecular beam epitaxy under different arsenic cracker conditions are studied by a Polaron doping profiles and secondary ion mass spectrometry. Throughout the doping range of investigation, 5X10 16 to 2X10 18 cm −3, strong reduction in Si incorporation is observed as the fraction of dimer arsenic is increased. The reduction of Si incorporation is enhanced as the growth temperature is increased. Evidence is given to show that, instead of Si self-compensation, Si dopants are actually desorbed in the presence of dimer arsenic. The formation of volatile Si xAs y compound(s) due to the reaction between the impinging dimer arsenic species and the Si dopants at the substrate surface may be responsible for this phenomenon. The activation energy of this reaction is estimated.