chemistry-2019-keynote

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allied
academies
May 13-14, 2019 | Prague, Czech Republic
Chemistry and Medicinal Chemistry
9th World Congress on
Page 26
Asian Journal of Biomedical and Pharmaceutical Sciences | Volume 9 ISSN: 2249-622X
P-type doped 4H-SiC with very low resistivity is still one
challenging technology in semiconducting fields. It is
well accepted that p-type doping of 4H silicon carbide (SiC)
by Al implantation and subsequent annealing results in
free charge carrier concentrations which are significantly
below what would be expected from activated and
ionized Al concentrations. This is commonly explained
by so-called compensating defects induced during the
implantation process and which remain after annealing.
Here, the experimentally determined compensation
ratio (i.e., the ratio of defect concentration to activated
Al concentration) is increasing with decreasing Al
concentration. Obviously, this compensation significantly
hinders the fabrication of todays and future SiC electron
devices where both, fabrication of regions with moderate
p-doping concentrations (such as p-well regions or junction
determination structures) where accurate concentrations
are required as well as regions where very high doping
concentrations (e.g., ohmic contacts) are required.
In this talk, Molecular Dynamics (MD) simulations, Raman
spectroscopy and sheet resistance measurements were used
to study the preparation processes of low-resistance p-type
4H-SiC by Al ion implantation with ion doses of 2.45×1012 -
9.0×1014 cm-2 and annealing treatment with temperatures of
1700 - 1900 °C. Greatly different from the LOPC (longitudinal
optical phonon-plasmon coupled) Raman mode found from
the sample of doping 4H-SiC during epitaxial growth, no
significant influence on the surface concentration could be
found for the longitudinal optical (LO) mode of Al-implanted
4H-SiC samples. When the Al surface concentration is larger
than around 1018 cm-3, it was found that the intensity of the
LO+ Raman peak (~ 980 - 1000 cm-1) increases and its full width
at half maximum (FWHM) drops with the increase of surface
concentrationafterannealingtreatment.Moreover,forsurface
concentrations above 1018 cm-3, the LO+ Raman peak showed
a left shift towards the LO peak, which could be related to
the increase of free carrier concentration in the Al-implanted
4H-SiC samples. After higher annealing temperatures of
1800 °C and 1900 °C, the crystallinity of Al-implanted 4H-SiC
was found to be improved compared to annealing at 1700
°C for surface concentrations larger than 10 18 cm-3, which is
consistent with the results of sheet resistance measurements.
Speaker Biography
Zongwei Xu, Dr. Engineering, has his expertise in Micro/nano
Manufacturing and Metrology. He was one of the pioneers of Micro/
nano Functional Structures Fabricated using Ion Beam Machining. He
has illustrated the Multi-parameters’ Coupling Mechanism involved
in nanoscale effects and developed several methodologies using Ion
Beam Nanofabrication. Several functional structures, including Siemens
Star Metrology template and Photomask Template in nanolithography,
have been developed and applied in Erlangen-Nuremberg University,
Germany, Mitutoyo Research Center Europe and Chinese Academy of
Sciences. More recently, he has conducted Activation of 4H-SiC p-type
Doping by Al Implantation and Subsequent Annealing - Simulation,
Characterization and Device Design Development. He is author of
over 60 papers, 6 book chapters on Micro/nano Manufacturing
and owner of 12 patents. He was the recipient of several Awards,
including “Newton Fund” granted by the Royal Society, “Young
Researchers” Awards (the 14th China-Japan International Conference
on Ultra-Precision Machining Process (CJUMP2018), and the 3rd Asian
Precision Engineering and Nanotechnology International Conference
(ASPEN2009)). He was the Associate Editor of Journal of Mechanical
Engineering Science, Guest Editor of Current Nanoscience, and the
Editorial Board Member of three International Journals.
e:
Zongwei Xu1
Mathias Rommel2
1Tianjin University, China
2Fraunhofer Institute for Integrated Systems and Device Technology IISB,
Germany
P-type 4H-SiC by Al Implantation and subsequent Annealing -
Simulation, characterization and device design development
Zongwei Xu et al., Asian J Biomed Pharmaceut Sci, Volume:9
DOI: 10.4066/2249-622X-C2-019