Nondestructive imaging of atomically thin nanostructures buried in silicon

It is now possible to create atomically thin regions of dopant atoms in silicon patterned with lateral dimensions ranging from the atomic scale (angstroms) to micrometers. These structures are building blocks of quantum devices for physics research and they are likely also to serve as key components of devices for next-generation classical and quantum information processing. Until now, the characteristics of buried dopant nanostructures could only be inferred from destructive techniques and/or the performance of the final electronic device; this severely limits engineering and manufacture of real-world devices based on atomic-scale lithography. Here, we use scanning microwave microscopy (SMM) to image and electronically characterize three-dimensional phosphorus nanostructures fabricated via scanning tunneling microscope–based lithography. The SMM measurements, which are completely nondestructive and sensitive to as few as 1900 to 4200 densely packed P atoms 4 to 15 nm below a silicon surface, yield electrical and geometric properties in agreement with those obtained from electrical transport and secondary ion mass spectroscopy for unpatterned phosphorus δ layers containing ~1013 P atoms. The imaging resolution was 37 ± 1 nm in lateral and 4 ± 1 nm in vertical directions, both values depending on SMM tip size and depth of dopant layers. In addition, finite element modeling indicates that resolution can be substantially improved using further optimized tips and microwave gradient detection. Our results on three-dimensional dopant structures reveal reduced carrier mobility for shallow dopant layers and suggest that SMM could aid the development of fabrication processes for surface code quantum computers.ISSN:2375-254

Quantitative sub-surface and non-contact imaging using scanning microwave microscopy

The capability of scanning microwave microscopy for calibrated sub-surface and non-contact capacitance imaging of silicon (Si) samples is quantitatively studied at broadband frequencies ranging from 1 to 20 GHz. Calibrated capacitance images of flat Si test samples with varying dopant density (1015–1019 atoms cm−3) and covered with dielectric thin films of SiO2 (100–400 nm thickness) are measured to demonstrate the sensitivity of scanning microwave microscopy (SMM) for sub-surface imaging. Using standard SMM imaging conditions the dopant areas could still be sensed under a 400 nm thick oxide layer. Non-contact SMM imaging in lift-mode and constant height mode is quantitatively demonstrated on a 50 nm thick SiO2 test pad. The differences between non-contact and contact mode capacitances are studied with respect to the main parameters influencing the imaging contrast, namely the probe tip diameter and the tip–sample distance. Finite element modelling was used to further analyse the influence of the tip radius and the tip–sample distance on the SMM sensitivity. The understanding of how the two key parameters determine the SMM sensitivity and quantitative capacitances represents an important step towards its routine application for non-contact and sub-surface imaging

Non-destructive imaging of atomically-thin nanostructures buried in silicon

Original data in support of our publication, "Non-destructive imaging of atomically-thin nanostructures buried in silicon"

Scanning microwave microscopy applied to semiconducting GaAs structures

International audienceA calibration algorithm based on one-port vector network analyzer (VNA) calibration for scanning microwave microscopes (SMMs) is presented and used to extract quantitative carrier densities from a semiconducting n-doped GaAs multilayer sample. This robust and versatile algorithm is instrument and frequency independent, as we demonstrate by analyzing experimental data from two different, cantilever- and tuning fork-based, microscope setups operating in a wide frequency range up to 27.5 GHz. To benchmark the SMM results, comparison with secondary ion mass spectrometry is undertaken. Furthermore, we show SMM data on a GaAs p-n junction distinguishing p- and n-doped layers

4070 km PM-8QAM Nyquist-WDM Transmission with 1.22x(Baud-Rate) Subcarrier Spacing over PSCF

Paper A2.

Transoceanic PM-QPSK Terabit Superchannel TransmissionExperiments at Baud-Rate Subcarrier Spacing

Paper We.7.C.

Studio sperimentale dell’impatto di ridotte spaziature inter-canale sulla trasmissione di un super-canale a 1 Terabit/s

paper A2.

Studio sperimentale dell'impatto di ridotte spaziature inter-canale sulla trasmissione di un super-canale a 1 Terabit/s

paper A2.

Transmission of 100 Gbit/s polarization multiplexed NRZ-QPSK over 2000 km of standard installed fiber with no optical dispersion compensation

We report on the transmission of a 100Gbit/s PM-QPSK signal on standard installed fiber over a distance of 2000km with no optical dispersion compensation. Using a digital coherent receiver a total dispersion of 32,600 ps/nm-km was compensated with 2dB OSNR penalt

100 Gbit/s WDM NRZ PM-QPSK long-haul transmission experiment over installed fiber probing non-linear reach with and without DCUs

Paper 3.4.