Growth of 3C-SiC using CS-PVT for application in power electronics and photonics
Wachstum von 3C-SiC mittels CS-PVT-Verfahren für die Anwendung in der Leistungselektronik und Photonik
Creators: name: Kollmuß, Manuel
Publisher: name: Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
Year: 2023
Subjects: Cubic Silicon Carbide
Close Space Physical Vapor Transport
Wafer Bow
Stress Analysis
Defect Density
Photonics
Bonding

description: This work contributes to the development of the 3C-SiC material system for application in power electronics and photonics. The emphasis was on improving material quality and the work can be divided into three parts. 1) First, a method to increase the diameter and thus the yield of 3C-SiC crystals is presented. Homoepitaxial chemical vapor deposition (CVD) grown 3C-SiC layers were used as seeding material and the challenges as well as solutions for the handling of the partly severely bent seed layers is discussed. Meanwhile the resulting crystals after close space physical vapor transport (CS-PVT) growth are optical flat and a reduction of the stress of the material could be verified by Raman spectroscopy measurements. The approach his compared to the growth on alternate seeding material with respect to upscale potential. The bow reduction mechanism observed during the CS-PVT was further investigated. For this purpose, Raman measurements on the seeding layers before and after the sublimation growth, as well as on the grown crystals was combined with X-Ray in situ visualization of the growth process to disclose the mechanism responsible for the flattening of the material. Further, high resolution X-Ray diffraction (HRXRD) was conducted to investigate the influence of unbending on the lattice planes of the crystals and to determine the resulting material quality based on the full width at half maximum (FWHM) of characteristic peaks from rocking curve measurements. 2) In the second part the influence of growth temperature, inert gas pressure and N2 doping level on the material quality of sublimation grown 3C-SiC is investigated in detail. The study was designed to systematically investigate the effect of the individual parameters independent of other influences. Optical microscopy, atomic force microscopy (AFM) and confocal laser scanning microscopy (LSM) were used to investigate the surface morphology while Raman spectroscopy was used to determine the charge carrier concentration and crystal quality. Additionally, all grown crystals as well as the used seeding layers were etched in molten KOH to deter-mine the influence of the growth parameters on the defect density. 3) Finally, utilization of 3C-SiC for photonic applications is demonstrated by the fabrication of a SiC-on-Isolator (SiCOI) material platform, suitable for photonic devices manufacturing. The growth of 3C-SiC on Si can be advantageous but also possess problems due to the high refractive index of Si. Therefore, starting form 3C-SiC grown heteroepitaxial on Si the substrate was removed wet chemically and the 3C-SiC thin film was bonded to a low refractive carrier material to form the SiCOI stack. Two different carrier materials and three bonding techniques (including an adhesive approach) were evaluated. The influence of various process parameters was analyzed to optimize the transfer process. Furthermore, the mechanism behind the successful combination of substrate and bonding approach is discussed.