Ferromagnetic nanoclusters hybridized in Mn-incorporated GaInAs layers duringmetal–organic vapour phase epitaxial growth on InP layers under low growth temperatureconditions

Abstract

We demonstrate the successful formation of ferromagnetic nanoclusters inMn-incorporated GaInAs layers grown by metal–organic vapour phase epitaxyon InP(100) substrates under low growth temperature conditions below450 °C. We find that MnAs nanoclusters with NiAs-type hexagonal crystallographic structures,which show ferromagnetic characteristics up to a relatively high temperature of about305 K, are formed near the layer surfaces of Mn-incorporated GaInAs layers grown at440 °C. After deposition of undoped InP layers on Mn-incorporated GaInAs layers,MnP nanoclusters with orthorhombic cubic crystallographic structures, in which7% arsenic is incorporated, are formed in InP layers. The samples with MnPnanoclusters show strong ferromagnetic coupling up to about 305 K, although theCurie temperature of MnP bulk compounds is 291 K. Energy dispersive x-rayspectroscopy (EDS) indicates that Mn concentrations in InP and GaInAs layers surroundingMnP nanoclusters are almost negligible. MnAs nanoclusters are also formed inMn-incorporated GaAs layers grown under low growth temperature conditions of450 °C on GaAs(100) substrates. From the results of magnetic characterizationswith respect to growth temperatures of the samples, we found thatall the Mn-incorporated GaAs layers grown at temperatures below450 °C showed ferromagnetic behaviour.