2,274 research outputs found
Hydrogen refinement during solid phase epitaxy of buried amorphous silicon layers
The effect of hydrogen on the kinetics of solid phase epitaxy (SPE) have been studied in buried amorphous Si layers. The crystallization rate of the front amorphous/crystalline (a/c) interface is monitored with time resolved reflectivity.Secondary ion mass spectrometry(SIMS) is used to examine H implanted profiles at selected stages of the anneals. The H retardation of the SPE rate is determined up to a H concentration of 2.3×10²⁰ cm¯³ where the SPE rate decreases by 80%. Numerical simulations are performed to model the H diffusion, the moving a/c interfaces and the refinement of the H profile at these interfaces. Despite the high H concentration involved, a simple Fickian diffusion model results in good agreement with the SIMS data. The segregation coefficient is estimated to be 0.07 at 575 °C. A significant fraction of the H escapes from the a-Si layer during SPE especially once the two a/c interfaces meet which is signified by the lack of H-related voids after a subsequent high temperature anneal.This research was supported by a grant from the Australian
Research Council
Deep level transient spectroscopy study for the development of ion-implanted silicon field-effect transistors for spin-dependent transport
A deep level transient spectroscopy (DLTS) study of defects created by
low-fluence, low-energy ion implantation for development of ion-implanted
silicon field-effect transistors for spin-dependent transport experiments is
presented. Standard annealing strategies are considered to activate the
implanted dopants and repair the implantation damage in test
metal-oxide-semiconductor (MOS) capacitors. Fixed oxide charge, interface
trapped charge and the role of minority carriers in DLTS are investigated. A
furnace anneal at 950 C was found to activate the dopants but did not
repair the implantation damage as efficiently as a 1000 C rapid
thermal anneal. No evidence of bulk traps was observed after either of these
anneals. The ion- implanted spin-dependent transport device is shown to have
expected characteristics using the processing strategy determined in this
study.Comment: 4 pages, 6 figure
A Robust Solution to the Super-Resolution Phase Problem in Scanning Transmission Electron Microscopy
From a set of images, each of poor resolution, recorded in a transmission microscope under many different incident angles of coherent illumination, it is possible to obtain wavelength-limited resolution even if there is a narrow aperture lying in the back-focal plane of the imaging lens. This is achieved by a deconvolution algorithm which retrieves the phase of the Fourier transform of the specimen. The method accounts for complex components in the transfer function of the lens, is not very sensitive to defocus and is remarkably resilient to noise. It may have important applications in overcoming the resolution limit in the scanning transmission electron microscope (STEM), where such data are readily available
Optical and electronic properties of sub-surface conducting layers in diamond created by MeV B-implantation at elevated temperatures
Boron implantation with in-situ dynamic annealing is used to produce highly
conductive sub-surface layers in type IIa (100) diamond plates for the search
of a superconducting phase transition. Here we demonstrate that high-fluence
MeV ion-implantation, at elevated temperatures avoids graphitization and can be
used to achieve doping densities of 6 at.%. In order to quantify the diamond
crystal damage associated with implantation Raman spectroscopy was performed,
demonstrating high temperature annealing recovers the lattice. Additionally,
low-temperature electronic transport measurements show evidence of charge
carrier densities close to the metal-insulator-transition. After electronic
characterization, secondary ion mass spectrometry was performed to map out the
ion profile of the implanted plates. The analysis shows close agreement with
the simulated ion-profile assuming scaling factors that take into account an
average change in diamond density due to device fabrication. Finally, the data
show that boron diffusion is negligible during the high temperature annealing
process.Comment: 22 pages, 6 figures, submitted to JA
Single-photon emitting diode in silicon carbide
Electrically driven single-photon emitting devices have immediate
applications in quantum cryptography, quantum computation and single-photon
metrology. Mature device fabrication protocols and the recent observations of
single defect systems with quantum functionalities make silicon carbide (SiC)
an ideal material to build such devices. Here, we demonstrate the fabrication
of bright single photon emitting diodes. The electrically driven emitters
display fully polarized output, superior photon statistics (with a count rate
of 300 kHz), and stability in both continuous and pulsed modes, all at room
temperature. The atomic origin of the single photon source is proposed. These
results provide a foundation for the large scale integration of single photon
sources into a broad range of applications, such as quantum cryptography or
linear optics quantum computing.Comment: Main: 10 pages, 6 figures. Supplementary Information: 6 pages, 6
figure
Engineering chromium related single photon emitters in single crystal diamond
Color centers in diamond as single photon emitters, are leading candidates
for future quantum devices due to their room temperature operation and
photostability. The recently discovered chromium related centers are
particularly attractive since they possess narrow bandwidth emission and a very
short lifetime. In this paper we investigate the fabrication methodologies to
engineer these centers in monolithic diamond. We show that the emitters can be
successfully fabricated by ion implantation of chromium in conjunction with
oxygen or sulfur. Furthermore, our results indicate that the background
nitrogen concentration is an important parameter, which governs the probability
of success to generate these centers.Comment: 14 pages, 5 figure
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