Optical and magnetic properties of Mn+-implanted GaAs

Neutron-transmutation-doped GaAs samples were prepared by irradiating the middle-level neutrons into the semi-insulating GaAs grown by a liquid encapsulated Czochralski method and subsequently implanted with Mn+. The characteristics of the Mn+-implanted neutron-transmutation-doped GaAs (namely, the implantation of Mn+ subsequent to neutron-transmutation-doping) were investigated by various measurements. The result of the energy dispersive x-ray peak displayed an injected Mn concentration of 9.65%. The photoluminescence peaks related to carbon and germanium acceptors were resolved, and the peaks related to Mn due to a neutral Mn acceptor were evidently observed. It is found that the proper activation for the neutral Mn acceptor starts from a relatively low annealing temperature of 600 deg. C for 15 min. The atomic force microscopy and magnetic forcemicroscopy images showed that magnetic clusters were well formed. The ferromagnetic hysteresis loop measured at 10 K was observed, and the temperature-dependent magnetization revealed that the two different phases exist at 135 and 360 K. The Curie temperature (Tc∼360 K) is caused by MnAs, which agrees with the clusters of the magnetic force microscopy image