An X-ray diffraction and Mössbauer study of interdiffusion phenomena at the interface between Fe and In_0.5Ga_0.5As (001)

¹ Laboratoire de Métallurgie Physique, UMR 6630 CNRS-Université de Poitiers, bâtiment SP2MI, Téléport 2, boulevard Marie et Pierre Curie, BP 30179, 86962 Futuroscope-Chasseneuil Cedex, France
² Groupe de Physique des Matériaux, UMR 6634 CNRS-Université de Rouen, Faculté des Sciences et des Techniques de Rouen, place Emile Blondel, 76821 Mont-Saint-Aignan Cedex, France

Corresponding author: jpeymery@univ-poitiers.fr

Received: 19 December 2001
Revised: 22 October 2002
Accepted: 14 November 2002
Published online: 27 February 2003

Abstract

Polycrystalline iron thin films on ion-etched monocrystalline In_0.5Ga_0.5As/InP (001) substrates were prepared using ion-beam sputtering deposition. The interface reaction was characterised by X-ray diffraction and conversion electron Mössbauer spectroscopy experiments, after annealing in vacuum for 1 h at temperatures between 350 and 450 °C. Interdiffusion phenomena mainly result in the formation of five new phases, namely metallic-In, InAs, Fe₂As, Fe₂In_xAs () and Fe₃GaAs_x (), in agreement with the predictions of the phase diagrams. InAs results from the decomposition of the semiconductor substrate and remains (001)-textured. The iron-arsenide grains grow into the substrate below the Fe/In_0.5Ga_0.5As interface. The In precipitates reach ~40 nm in size after 1 h annealing at 450 °C, while the Fe₃GaAs_x phase appears at 400–450 °C with an either textured or disordered structure. Finally, the overall activation energy for the thermal reaction is calculated to be 1.5 eV in the latter temperature range.