Characteristics of FeSi

Self-assembled β-FeSi2 quantum (QD) dots were grown on n-type Si and investigated in this work. Secondary electron images show the shape and distribution of the quantum dots depends on the temperature and thickness of the Fe deposition. Electrical characteristics were measured in MIS devices prepared by covering the quantum dots by an oxide or by a photoresist layer. The cold deposited and subsequently annealed Fe layers were found to generate large concentration of deep level defects, compensating the upper few microns layer of the silicon wafer. Reactive deposition epitaxy (RDE) growth of QDs – where the iron is deposited on hot substrate—generated much lower concentration of defect, in some devices with characteristics comparable to the reference wafer. The significant scatter on the surface is attributed to inhomogeneous growth conditions and to residual surface contamination on the surface

Nanoscale morphology and photoemission of arsenic implanted germanium films

Germanium films of 140 nm thickness deposited onto Si substrate were implanted with 70 keV arsenic ions with a dose of 2.5x10(14) cm(-2). The morphology of the implanted films was determined by Rutherford backscattering and cross-sectional transmission electron microscopy. Concentration of oxygen and carbon impurities and their distribution in the implanted layer were detected by secondary-ion-mass spectroscopy and nuclear reaction analysis using the O-16(He-4,He-4)O-16 reaction. The depth dependence of the valence band density of states was investigated by measuring the energy distribution curve of photoelectrons using Ar ion etching for profiling. The morphology of As implanted film was dominated by nanosized (10-100 nm) Ge islands separated by empty bubbles at a depth of 20-50 nm under the surface. At depth ranges of 0-20 and 70 to a measured depth of 140 nm, however, morphology of the as-evaporated Ge film was not modified. At a depth of 20-50 nm, photoelectron spectra were similar to those obtained for Ge amorphized with heavy ion (Sb) implantation [implantation induced (I.I.) a-Ge]. The depth profile of the morphology and the photoemission data indicate correlation between the morphology and valence band density of states of the ion I.I. a-Ge. As this regime was formed deep in the evaporated film, i.e., isolated from the environment, any contamination, etc., effect can be excluded. The depth distribution of this I.I. a-Ge layer shows that the atomic displacement process cannot account for its formation