61 research outputs found
The effect of low-energy ion-implantation on the electrical transport properties of Si-SiO2 MOSFETs
Using silicon MOSFETs with thin (5nm) thermally grown SiO2 gate dielectrics,
we characterize the density of electrically active traps at low-temperature
after 16keV phosphorus ion-implantation through the oxide. We find that, after
rapid thermal annealing at 1000oC for 5 seconds, each implanted P ion
contributes an additional 0.08 plus/minus 0.03 electrically active traps,
whilst no increase in the number of traps is seen for comparable silicon
implants. This result shows that the additional traps are ionized P donors, and
not damage due to the implantation process. We also find, using the room
temperature threshold voltage shift, that the electrical activation of donors
at an implant density of 2x10^12 cm^-2 is ~100%.Comment: 11 pages, 10 figure
Electrically detected magnetic resonance using radio-frequency reflectometry
The authors demonstrate readout of electrically detected magnetic resonance
at radio frequencies by means of an LCR tank circuit. Applied to a silicon
field-effect transistor at milli-kelvin temperatures, this method shows a
25-fold increased signal-to-noise ratio of the conduction band electron spin
resonance and a higher operational bandwidth of > 300 kHz compared to the kHz
bandwidth of conventional readout techniques. This increase in temporal
resolution provides a method for future direct observations of spin dynamics in
the electrical device characteristics.Comment: 9 pages, 3 figure
Electrically-detected magnetic resonance in ion-implanted Si:P nanostructures
We present the results of electrically-detected magnetic resonance (EDMR)
experiments on silicon with ion-implanted phosphorus nanostructures, performed
at 5 K. The devices consist of high-dose implanted metallic leads with a square
gap, into which Phosphorus is implanted at a non-metallic dose corresponding to
10^17 cm^-3. By restricting this secondary implant to a 100 nm x 100 nm region,
the EDMR signal from less than 100 donors is detected. This technique provides
a pathway to the study of single donor spins in semiconductors, which is
relevant to a number of proposals for quantum information processing.Comment: 9 pages, 3 figure
- and -spin relaxation time limitations of phosphorous donor electrons near crystalline silicon to silicon dioxide interface defects
A study of donor electron spins and spin--dependent electronic transitions
involving phosphorous (P) atoms in proximity of the (111) oriented
crystalline silicon (c-Si) to silicon dioxide (SiO) interface is
presented for [P] = 10 and [P] =
10 at about liquid He temperatures (
). Using pulsed electrically detected magnetic
resonance (pEDMR), spin--dependent transitions between the \Phos donor state
and two distinguishable interface states are observed, namely (i) \Pb centers
which can be identified by their characteristic anisotropy and (ii) a more
isotropic center which is attributed to E defects of the \sio bulk
close to the interface. Correlation measurements of the dynamics of
spin--dependent recombination confirm that previously proposed transitions
between \Phos and the interface defects take place. The influence of these
electronic near--interface transitions on the \Phos donor spin coherence time
as well as the donor spin--lattice relaxation time is then
investigated by comparison of spin Hahn--echo decay measurements obtained from
conventional bulk sensitive pulsed electron paramagnetic resonance and surface
sensitive pEDMR, as well as surface sensitive electrically detected inversion
recovery experiments. The measurements reveal that both and of
\Phos donor electrons spins in proximity of energetically lower interface
states at K are reduced by several orders of magnitude
Tailored nanodiamonds for hyperpolarized ¹³C MRI
Nanodiamond is poised to become an attractive material for hyperpolarized ¹³C magnetic resonance imaging if large nuclear polarizations can be achieved without the accompanying rapid spin-relaxation driven by paramagnetic species. Here we report enhanced and long-lived ¹³C polarization in synthetic nanodiamonds tailored by acid-cleaning and air-oxidation protocols. Our results separate the contributions of different paramagnetic species on the polarization behavior, identifying the importance of substitutional nitrogen defect centers in the nanodiamond core. These results are likely of use in the development of nanodiamond-based imaging agents with size distributions of relevance for examining biological processes
Broadband electrically detected magnetic resonance of phosphorus donors in a silicon field-effect transistor
We report electrically detected magnetic resonance of phosphorus donors in a
silicon field-effect transistor. An on-chip transmission line is used to
generate the oscillating magnetic field allowing broadband operation. At
milli-kelvin temperatures, continuous wave spectra were obtained up to 40 GHz,
using both magnetic field and microwave frequency modulation. The spectra
reveal the hyperfine-split electron spin resonances characteristic for Si:P and
a central feature which displays the fingerprint of spin-spin scattering in the
two-dimensional electron gas.Comment: 4 pages, 4 figures, submitted to AP
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