Temperature-dependent Hall effect measurements on Cz-grown silicon pulled from compensated and recycled feedstock materials

Abstract

In this work, temperature-dependent Hall effect measurements in the temperature range 88–350K were carried out to investigate the electrical properties of three solar grade p-type Czochralski (Cz) silicon ingots, pulled from recycled p-type multi-crystalline silicon top cuts and compensated solar grade (SoG) feedstock. Material bulk properties including Hall mobility, carrier density and resistivity as functions of temperature were studied to evaluate the influence of compensation and impurities.Recycled top cut replacing poly-silicon as feedstock leads to a more uniform resistivity. In addition, higher concentrations of O and C, give rise to oxygen related defects, which act as neutral scattering centers displaying only a slight influence on the electrical properties at low temperature compared to the dominant compensation effect.The electrical performances of all samples are shown to be strongly dependent on compensation level, especially at the lowest temperature (~88K). A significant presence of incompletely ionized phosphorus was deduced through the measured carrier density. The temperature-dependent Hall effect measurements fit Klaassen׳s mobility model very well at low temperatures (<150K), showing consistency with the explanation of a reduced screening effect on ionized dopants for lightly doped silicon, while the deviation at the high temperature probably may be accounted for by the presence of as-grown defects, such as oxygen related defects and phosphorus clusters, which are usually neglected in most mobility models.