Electrically active defects induced by sputtering deposition on silicon: The role of hydrogen

摘要

We present a study of the electrically active defects produced in p-type silicon crystals underneath a titanium layer deposited by sputtering to form a Schottky contact. The defects were investigated by Deep Level Transient Spectroscopy and free carrier profiles were determined by Capacitance-Voltage measurements. The sputtering deposition experiments were performed on silicon crystals grown either by Molecular Beam Epitaxy (MBE) or by the Czochralski technique (Cz). All the layers contained hydrogen as a result of normal cleaning and etching procedures. In MBE-grown silicon, four defects were observed referred to as H(0.61), H(0.52), H(0.33), and H(0.23). H(0.23) has been identified as the donor level of the divacancy, while it has been shown that the three other defects were boron-related. In the Cz-grown silicon crystals only H(0.52) has been observed. This defect is hydrogen-related in addition to its correlation with boron. In both MBE and Cz grown crystals, the H(0.52) defect displayed a bell-shape distribution while the three other defects follow profiles decaying exponentially from the surface. We propose that H(0.52) is B_(i)-B_(s)-H formed by the capture of B_(i) at a hydrogen passivated B_(s) site.