Deeper insight into lifetime-engineering in 4H-SiC by ion implantation

Lifetime-engineering in 4H-SiC is important to obtain a low forward voltage drop in bipolar devices with high blocking voltages above 10 kV. It is known that the implantation of carbon and subsequent thermal annealing can be used to improve the minority carrier lifetime of as-grown epitaxial layers due to annihilation of carbon vacancies and, therefore, reduce the lifetime limiting defect Z 1 / 2. In this paper, the ion implantation of other ions (N, Al, B, and As) besides carbon and their impact on minority carrier lifetime and point defect concentration are shown. Special attention is paid to the effect of ion implantation with subsequent electrical activation by high temperature annealing. A strong influence of the implantation dose and, therefore, corresponding resulting doping concentration was found. A lifetime enhancement could be found for some implanted species for higher implantation doses whereas the detrimental effect of high temperature annealing dominated at low implantation doses. The results reveal that the implantation dose and the occupied lattice sites are important parameters to achieve a lifetime enhancement. A model is presented which explains the different impacts of various implanted ions and a more detailed understanding of lifetime-engineering by ion implantation. With this knowledge, it was possible to reduce the detrimental Z 1 / 2 defect in a large part of thick epitaxial layers with conventional shallow ion implantation and high temperature annealing. Consequently, the minority carrier lifetimes of the epitaxial layers could be enhanced

Characterization of grain boundaries in multicrystalline silicon with high lateral resolution using conductive atomic force microscopy

In this work, the electrical characteristics of grain boundaries (GBs) in multicrystalline silicon with and without iron contamination are analyzed by fixed voltage current maps and local I/V curves using conductive AFM (cAFM). I/V characteristics reveal the formation of a Schottky contact between the AFM tip and the sample surface. The impact of both, the polarity of the applied voltage and the illumination by the AFM laser on the behavior of GBs was analyzed systematically. Depending on the polarity of the applied voltage and the iron content of the sample, grain boundaries alter significantly the recorded current flow compared to the surrounding material. The results also show a clear influence of the AFM laser light on the electrical behavior of the grain boundaries. Conductive AFM measurements are furthermore compared to data obtained by electron beam induced current (EBIC), indicating that cAFM provides complimentary information

Laser Writing of Scalable Single Color Centers in Silicon Carbide

Single photon emitters in silicon carbide (SiC) are attracting attention as quantum photonic systems (Awschalom et al. Nat. Photonics 2018, 12, 516−527; Atatüre et al. Nat. Rev. Mater. 2018, 3, 38–51). However, to achieve scalable devices, it is essential to generate single photon emitters at desired locations on demand. Here we report the controlled creation of single silicon vacancy (VSi) centers in 4H-SiC using laser writing without any postannealing process. Due to the aberration correction in the writing apparatus and the nonannealing process, we generate single VSi centers with yields up to 30%, located within about 80 nm of the desired position in the transverse plane. We also investigated the photophysics of the laser writing VSi centers and concluded that there are about 16 photons involved in the laser writing VSi center process. Our results represent a powerful tool in the fabrication of single VSi centers in SiC for quantum technologies and provide further insights into laser writing defects in dielectric materials

Laser Writing of Scalable Single Color Centers in Silicon Carbide_Dataset

This file corresponds to data used in the publication "Laser Writing of Scalable Single Color Centers in Silicon Carbide", Nano Letters (2019) DOI: 10.1021/acs.nanolett.8b05070. It is the data used to generate the plots shown in the Figures. Plots of the 2D photoluminessence from the confocal microscope are presented in Python format, the rest is readable as ASCi file format

Impact of Al-ion implantation on the formation of deep defects in n-type 4H-SiC

In this work, deep defects in an aluminum implanted 4H-SiC n-type epitaxy are discussed in dependence on following influencing factors: concentration of implanted aluminum, implantation energy, implantation at 500°C and at room temperature, as well as ascending or descending order of implantation energies during ion implantation using Gaussian profiles. The compensation ratio, which reaches values up to 90% of the implanted aluminum concentration, is determined by Hall Effect measurements. Compensating defect centers (Z1/2-, ONx-defects) are detected by Deep Level Transient Spectroscopy after high energy ion implantation using an energy filter, followed by an annealing and an oxidation process