Verfahren zum Bearbeiten eines Substrats

EP 2009426 A2 UPAB: 20090130 NOVELTY - The method (700) involves treating defects in the substrate material. A transmission measurement of the substrate is carried out to obtain a transmission value, which is a measurement for the defects in the substrate material (710). The processing of the substrate is actuated depending on the transmission value (720). The measurement for the defects is a measurement for a number and depth of the defects. The substrate materials are gallium nitride, aluminum nitride, alumina, or other transparent semiconductor materials. USE - Method for processing a substrate from a substrate material. ADVANTAGE - The transmission measurement of the substrate is carried out to obtain a transmission value, which is a measurement for the defects in the substrate material and the processing of the substrate is actuated depending on the transmission value, and hence ensures direct control or regulation of the treatment processes or material synthesis processes and a cost effective manufacturing and process development in the field of research and development

Crystal growth of compound semiconductors with low dislocation densities

This paper will highlight some technological developments in the field of Vertical Gradient Freeze growth of InP and GaAs for providing substrates with low dislocation densities. Furthermore, the role of micropipes and basal plane dislocations during sublimation and epitaxial growth of SiC will be addressed. Finally, different strategies will be illustrated to achieve GaN with high structural perfection

Optical stressing of 4H-SiC material and devices

Electrical testing with regard to bipolar degradation of high voltage SiC devices cannot be done on wafer level, but only expensively after module assembly. We show that 4H-SiC material can be optically stressed by applying high UV laser intensities, i.e., bipolar degradation as in electrical stress tests can be provoked on wafer level. Therefore, optical stressing can be used for control measurements and reliability testing. Different injection (=stress) levels have been used similar to the typical doping level of the base material and similar to the established electrical stress test. The analysis of degradation is done by photoluminescence imaging, which is a wellestablished technique for revealing structural defects such as Basal Plane Dislocations (BPDs) and Stacking Faults (SFs) in 4H-SiC epiwafers and partially processed devices

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

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