Pontus Stenberg

Vector Magnetometry Using Silicon Vacancies in 4 H -SiC Under Ambient Conditions

The spins of point defects in silicon carbide are promising candidates for qubits and sensors under

High-Resolution Raman and Luminescence Spectroscopy of Isotope-Pure 28Si12C, Natural and 13C – Enriched 4H-SiC

a\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}b\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}t

Matching precursor kinetics to afford a more robust CVD chemistry: a case study of the C chemistry for silicon carbide using SiF4 as Si precursor

conditions. Unlike defect-bearing diamond, SiC is regarded as an industry-friendly platform, with an existing market for high-purity SiC wafers and a mature fabrication technology. The authors detect the magnitude and direction of a magnetic field using magnetic resonance with optical readout of the spin-3/2 states of silicon-vacancy defects in SiC, plus optimized pulse sequences for spin manipulation. This yields a solid-state quantum vector magnetometer in a material available for wafer-scale production.

Donor and double-donor transitions of the carbon vacancy related EH6∕7 deep level in 4H-SiC

The optical properties of isotope-pure 28Si12C, natural SiC and enriched with 13C isotope samples of the 4H polytype are studied by means of Raman and photoluminescence spectroscopies. The phonon energies of the Raman active phonons at the Γ point and the phonons at the M point of the Brillouin zone are experimentally determined. The excitonic bandgaps of the samples are accurately derived using tunable laser excitation and the phonon energies obtained from the photoluminescence spectra. Qualitative comparison with previously reported results on isotope-manipulated Si is presented.

Fast Growth Rate Epitaxy on 4° Off-Cut 4-Inch Diameter 4H-SiC Wafers

Chemical Vapor Deposition (CVD) is one of the technology platforms forming the backbone of the semiconductor industry and is vital in the production of electronic devices. To upscale a CVD process from the lab to the fab, large area uniformity and high run-to-run reproducibility are needed. We show by a combination of experiments and gas phase kinetics modeling that the combinations of Si and C precursors with the most well-matched gas phase chemistry kinetics gives the largest area of of homoepitaxial growth of SiC. Comparing CH4, C2H4 and C3H8 as carbon precursors to the SiF4 silicon precursor, CH4 with the slowest kinetics renders the most robust CVD chemistry with large area epitaxial growth and low temperature sensitivity. We further show by quantum chemical modeling how the surface chemistry is impeded by the presence of F in the system which limits the amount of available surface sites for the C to adsorb.

Defects in silicon carbide grown by fluorinated chemical vapor deposition chemistry

Using medium- and high-resolution multi-spectra fitting of deep level transient spectroscopy (DLTS), minority carrier transient spectroscopy (MCTS), optical O-DLTS and optical-electrical (OE)-MCTS measurements, we show that the EH6∕7 deep level in 4H-SiC is composed of two strongly overlapping, two electron emission processes with thermal activation energies of 1.49 eV and 1.58 eV for EH6 and 1.48 eV and 1.66 eV for EH7. The electron emission peaks of EH7 completely overlap while the emission peaks of EH6 occur offset at slightly different temperatures in the spectra. OE-MCTS measurements of the hole capture cross section σp0(T) in p-type samples reveal a trap-Auger process, whereby hole capture into the defect occupied by two electrons leads to a recombination event and the ejection of the second electron into the conduction band. Values of the hole and electron capture cross sections σn(T) and σp(T) differ strongly due to the donor like nature of the deep levels and while all σn(T) have a negative tempe...

Incorporation of dopants in epitaxial SiC layers grown with fluorinated CVD chemistry

We report the development of over 100 μm/h growth rate process on 4-inch diameter wafers using chlorinated growth. The optimized growth process has shown extremely smooth epilayers completely free of surface step-bunching with very low surface defect density, high uniformity in thickness and doping and high run to run reproducibility in growth rate, controlled doping and defect density.

Morphology Optimization of Very Thick 4H-SiC Epitaxial Layers

Abstract Point defects in n- and p-type 4H-SiC grown by fluorinated chemical vapor deposition (CVD) have been characterized optically by photoluminescence (PL) and electrically by deep-level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS). The results are considered in comparison with defects observed in non-fluorinated CVD growth (e.g., using SiH4 instead of SiF4 as silicon precursor), in order to investigate whether specific fluorine-related defects form during the fluorinated CVD growth, which might prohibit the use of fluorinated chemistry for device-manufacturing purposes. Several new peaks identifying new defects appear in the PL of fluorinated-grown samples, which are not commonly observed neither in other halogenated chemistries, nor in the standard CVD chemistry using silane (SiH4). However, further investigation is needed in order to determine their origin and whether they are related to incorporation of F in the SiC lattice, or not. The electric characterization does not find any new electrically-active defects that can be related to F incorporation. Thus, we find no point defects prohibiting the use of fluorinated chemistry for device-making purposes.

Silicon Chemistry in Fluorinated Chemical Vapor Deposition of Silicon Carbide

Fluorinated chemistry in chemical vapor deposition (CVD) of silicon carbide (SiC) with SiF4 as Si precursor has been shown to fully eliminate the formation of silicon clusters in the gas phase, making SiF4 an interesting Si precursor. However, before a fluorinated CVD chemistry can be adopted, the effect of fluorine on the dopant incorporation must be understood since dopant incorporation is of paramount importance in semiconductor manufacturing. Here, the authors present dopant incorporation studies for n-type doping with N using N2 and p-type doping with Al using TMAl in fluorinated CVD of homoepitaxial SiC. The precursors used were SiF4 as Si precursor and the source of F together with CH4 as C precursor. The authors find that it is possible to control the doping in SiC epitaxial layers when using a fluorinated CVD chemistry for both n- and p-type materials using the C/Si ratio as in standard SiC CVD. However, large area doping uniformity seems to be a challenge for a fluorinated CVD chemistry, most li...

Process stability and morphology optimization of very thick 4H-SiC epitaxial layers grown by chloride-based CVD

Epitaxial growth of about 200 µm thick, low doped 4H-SiC layers grown on n-type 8° off-axis Si-face substrates at growth rates around 100 µm/h has been done in order to realize thick epitaxial layers with excellent morphology suitable for high power devices. The study was done in a hot wall chemical vapor deposition reactor without rotation. The growth of such thick layers required favorable pre-growth conditions and in-situ etch. The growth of 190 µm thick, low doped epitaxial layers with excellent morphology was possible when the C/Si ratio was below 0.9. A low C/Si ratio and a favorable in-situ etch are shown to be the key parameters to achieve 190 µm thick epitaxial layers with excellent morphology.