MBE growth and properties of 3d transition metal-doped GaAs

Heavy 3d transition metal impurity doping into GaAs has been studied by low temperature molecular beam epitaxy. Temperature dependence of conductivities on 3d transition metal impurity doped layers have been well fitted by View the MathML source, suggesting that variable range hopping in impurity band with soft Coulomb gap is dominant. Super paramagnetic behavior observed in Cr-doped GaAs has been suggested for local ferromagnetic spin ordering, while both Fe- and Co-doped GaAs layers are paramagnetic in the temperature range from room temperature to 2 K.