arXiv subjects

Sergey Rubanov

Publications and source records attributed to Sergey Rubanov.

6 recordsLinked to original sources

arXiv2026

Efficient and Robust p-type Transistor based on Ultra-wide-bandgap Semiconductor

The p-type transistor is an indispensable component of semiconductor technology, enabling complementary operation with n-channel transistors for computation, storage, and communication. Achieving both high robustness and high efficiency is highly desirable but challenging for p-type transistors due to limited semiconductors with reliable hole transport and their high activation energies. Here, we achieved a robust yet efficient p-type transistor by heterogeneously integrating an ultra-wide-bandgap semiconductor and a high-k dielectric layer through van der Waals integration. The p-type transistor employs a two-dimensional hole channel on hydrogenated diamond (bandgap 5.6 eV) combined with a high-k (30.5) SrTiO3 perovskite membrane. At room temperature, the transistor exhibits stable operation with a high on-current (~200 mA/mm), low subthreshold swing (70 mV/dec), high hole mobility (566 cm^2/Vs to 572 cm^2/Vs) and high on-off ratio (~10^9). Furthermore, tuning annealing temperature allows operation in either enhancement or depletion mode. The robust p-type transistor with high efficiency holds great potential for future power electronics, UV optoelectronics, and harsh-environment electronic applications.

cond-mat.mtrl-sci↗

arXiv2025

A silicon spin vacuum: isotopically enriched $^{28}$silicon-on-insulator and $^{28}$silicon from ultra-high fluence ion implantation

Isotopically enriched silicon (Si) can greatly enhance qubit coherence times by minimizing naturally occurring $^{29}$Si which has a non-zero nuclear spin. Ultra-high fluence $^{28}$Si ion implantation of bulk natural Si substrates was recently demonstrated as an attractive technique to ultra-high $^{28}$Si isotopic purity. In this work, we apply this $^{28}$Si enrichment process to produce $^{28}$Si and $^{28}$Si-on-insulator (SOI) samples. Experimentally, we produced a $^{28}$Si sample on natural Si substrate with $^{29}$Si depleted to 7~ppm (limited by measurement noise floor), that is at least 100 nm thick. This is achieved with an ion energy that results in a sputter yield of less than one and an ultra-high ion fluence, as supported by our improved computational model that is based on fitting a large number of experiments. Further, our model predicts the $^{29}$Si and $^{30}$Si depletion in our sample to be less than 1~ppm. In the case of SOI, ion implantation conditions are found to be more stringent than those of bulk natural Si in terms of minimizing threading dislocations upon subsequent solid phase epitaxy annealing. Finally, we do not observe open volume defects in our $^{28}$SOI and $^{28}$Si samples after SPE annealing (620°C, 10 minutes).

cond-mat.mtrl-sci↗

arXiv2024

In-situ Investigation of the Phase Formation and Superconductivity in V$_3$Si Thin Films at High Temperatures

Vanadium silicide (V$_3$Si) is a promising superconductor for integration with silicon-based electronics, however the interfacial growth kinetics have a strong influence on the resulting superconducting properties and are not yet fully understood. In this study, we have used neutron reflectometry to reveal the phase transformation during thin film growth driven by different annealing strategies. We examined the silicide formation when a thin layer of vanadium undergoes reactive diffusion with a silicon dioxide film on silicon at temperatures from 650-800 °C. To further investigate the time evolution of different phases under various annealing temperatures, a chemical model was developed and subsequent simulations were performed. The results of this model were validated using X-ray diffraction and cross-sectional TEM analysis. Correlations were observed between the structure and superconducting properties. Over-annealing films leads to complete depletion of the SiO$_2$ barrier layer, forming diffuse interfaces and driving the formation of undesirable silicon-rich silicides. Avoiding this by controlling time and temperature, allows higher quality superconducting films to be achieved. The $T_c$ of the films was found to be 13 K, and the annealing conditions influenced the critical fields and the paramagnetic Meissner effect near $T_c$. For optimally-annealed films, superconducting order parameters were calculated. Ginzberg-Landau theory was applied to explain flux penetration.

cond-mat.supr-con↗

arXiv2015

A TEM study of Si-SiO2 interfaces in silicon nanodevices

The fabrication of micro- and nano-scale silicon electronic devices requires precision lithography and controlled processing to ensure that the electronic properties of the device are optimized. Importantly, the Si-SiO2 interface plays a crucial role in defining these properties. While transmission electron microscopy (TEM) can be used to observe the device architecture, substrate / contact crystallinity and interfacial roughness, the preparation and isolation of the device active area is problematic. In this work, we describe the use of focussed ion beam technologies to isolate and trench-cut targeted device structures for subsequent TEM analysis. Architectures studied include radio frequency, single electron transistors and electrically detected, magnetic resonance devices that have also undergone ion implantation, rapid thermal and forming gas anneals.

cond-mat.mtrl-sci↗

arXiv2013

Direct measurement and modelling of internal strains in ion-implanted diamond

We present a phenomenological model and Finite Element simulations to describe the depth variation of mass density and strain of ion-implanted single-crystal diamond. Several experiments are employed to validate the approach: firstly, samples implanted with 180 keV B ions at relatively low fluences are characterized using high-resolution X-ray diffraction (HR-XRD); secondly, the mass density variation of a sample implanted with 500 keV He ions well above its amorphization threshold is characterized with Electron Energy Loss Spectroscopy (EELS). At high damage densities, the experimental depth profiles of strain and density display a saturation effect with increasing damage and a shift of the damage density peak towards greater depth values with respect to those predicted by TRIM simulations, which are well accounted for in the model presented here. The model is then further validated by comparing TEM-measured and simulated thickness values of a buried amorphous carbon layer formed at different depths by implantation of 500 keV He ions through a variable-thickness mask to simulate the simultaneous implantation of ions at different energies.

cond-mat.mtrl-sci↗

arXiv2006

Coherent Population Trapping in Diamond N-V Centers at Zero Magnetic Field

Coherent population trapping at zero magnetic field was observed for nitrogen-vacancy centers in diamond under optical excitation. This was measured as a reduction in photoluminescence when the detuning between two excitation lasers matched the 2.88 GHz crystal-field splitting of the color center ground states. This behavior is highly sensitive to strain, which modifies the excited states, and was unexpected following recent experiments demonstrating optical readout of single nitrogen-vacancy electron spins based on cycling transitions. These results demonstrate for the first time that three-level Lambda configurations suitable for proposed quantum information applications can be realized simultaneously for all four orientations of nitrogen-vacancy centers at zero magnetic field.

cond-mat.mes-hall↗