Contactless electrical defect characterization and topography of a-plane grown epitaxial layers

摘要

Two novel techniques for the electrical characterization of SiC samples and wafers are introduced. Microwave detected photo induced current transient spectroscopy (MD-PICTS) is used to investigate properties of deep defects similar to conventional PICTS and deep level transient spectroscopy (DLTS). In microwave detected photoconductivity (MDP), electrical properties like minority carrier lifetime τ, drift mobility μ, and diffusion length L can be mapped over a wafer at room temperature. The advantage of both techniques is that they do not require the investigated sample to be contacted. Thus, wafers can be characterized non-destructively and spatially resolved. MD-PICTS spectra of three sublimation grown epilayers, two on a-plane substrates and one on a commercial c-oriented substrate, are presented and compared to their PL-spectra. In addition, both MDP- and PL-topograms of one sample are shown. The applicability of the techniques to various types of SiC samples (bulk or epilayer, n-type, p-type, semi-insulating) is discussed.