Erbium-substituted Srl-xErxF2+x strontium fluoride layers were grown on InP(100) substrates by sublimation under ultra-high vacuum of high purity solid solution powders.

Their composition and the spatial distribution of the basic components were deduced from Rutherford backscattering (RBS), using a nuclear microprobe, and secondary ion mass spectrometry (SIMS). For x lower than 20% it is shown that the film composition is analogous with the initial sintered material and quite homogeneous. The ageing in air of the films was followed by infrared absorption studies. No significant water adsorption was revealed.

The texture of the layers was studied by RBS in channelling condition. For x as high as 15% it is shown that the films are well crystallized and well epitaxially grown on InP (100) substrates.

Infrared emission due to the 4I13/2-4I15/2 electronic transition on the 4f11 inner shells of Er3+ ions (1.53μm), which presents potential applications for optical communications, was studied at room temperature as a function of x. It is demonstrated that the highest luminescence efficiency of these layers corresponds to x upper than 20%.

The chemical species present at the surface of InP substrates at the different stages of a classical cleaning (degreasing, etching, de-oxidation and UHV annealing) were studied by infrared absorption (IR). Traces of oxides were detected from nuclear reaction analysis (NRA). With these analysis techniques, after the complete treatment, no defects were revealed at the surface of the substrates. RHEED patterns showed that they were well-reconstructed and SrF2 thin films were succesfully epitaxially grown on the semiconductor. However, capacitancevoltage (C-V) measurements performed on MIS (SrF2/InP) structures showed that to obtain a large modulation of the surface potential of the semiconductor, a sulfurization of the substrates ((NH4)2Sx) was required after the etching phase. These results show that many complementary analysis techniques must be used to completely describe the surface state of a cleaned semiconductor.