Electron IMFPs in bulk Cd 0.88Mn 0.12Te crystals determined by EPES

Abstract

The inelastic mean free path (IMFP) of electrons is a basic parameter for surface-sensitive electron spectroscopies (AES, XPS, EELS) in quantitative analyses. Cd 1− x Mn x Te mixed crystals are currently of great interest due to their magnetic and magneto-optical properties. Since information on electron transport processes in these semimagnetic compounds is scarce, their systematic studies are highly desirable. In the present work, the IMFPs in Cd 0.88Mn 0.12Te (1 1 0) crystal samples were obtained from EPES with use of the Ni standard in the electron energy range 500–2000 eV. In addition, we also explored the effect of bulk Mn content in the determination of the IMFP. Relative EPES measurements were carried out using the MICROLAB 350 spectrometer. The sample surface was sputter cleaned and amorphized by Ar + ions. Surface composition of the samples was monitored in situ by XPS and AES. The measured IMFPs were uncorrected for surface excitations and compared with those predicted from the TPP-2M and G-1 formulae. Also, the values of the IMFPs determined here were compared with those evaluated from the expression of Sekine et al. However, accuracy of this expression is rather poor except the case of pure CdTe ( x = 0). In general, good agreement was found between the measured IMFPs in Cd 0.88Mn 0.12Te and the corresponding predicted IMFPs. The root-mean-square deviation from IMFP values predicted from the TPP-2M formula was 1.2 Å. The mean percentage deviation from the TPP-2M IMFPs was 9.3%.