We experimentally demonstrate a method for obtaining nuclear spin hyperpolarization, that is, polarization significantly in excess of that expected for a thermal equilibrium. By exploiting a modified Overhauser process, we obtain more than 68% nuclear anti-polarization of phosphorus donors in silicon. This polarization is reached with a time constant of ~150 seconds, at a temperature of 1.37 K and a magnetic field of 8.5 T. The ability to obtain such large polarizations is discussed with regards to its significance for quantum information processing and magnetic resonance imaging.
Spin-Dependent Recombination between Phosphorus Donors in Silicon and Si/SiO2 Interface States Investigated with Pulsed Electrically Detected Electron Double Resonance
A comprehensive model of high-concentration phosphorus diffusion has been developed and simulation of phosphorus diffusion from a constant source (phosphosilicate glass) at a temperature of 890 Celsius degrees for 14.25 min. has been carried out. Such doping processes are widely used in manufacturing modern solar cells. The proposed model combines the ideas of the drift of silicon self-interstitials in the field of elastic stresses with the concept of the formation of negatively charge clusters of impurity atoms. The calculated phosphorus concentration profile is in good agreement with the exp…
The controlled creation of color centers in phosphorus-doped (n-type) diamond can facilitate the electronics integration of quantum photonics devices, such as single-photon sources operating upon electrical injection. Silicon vacancy (SiV) color centers are promising candidates, but so far the conditions for single-photon emission in phosphorus-doped diamond have not been investigated. In this study, we create SiV color centers in diamond samples with different phosphorus concentrations and show that the fluorescence background due to doping, nitrogen-impurities and ion implantation induced de…
Modulation of donor electron wavefunction via electric fields is vital to quantum computing architectures based on donor spins in silicon. For practical and scalable applications, the donor-based qubits must retain sufficiently long coherence times in any realistic experimental conditions. Here, we present pulsed electron spin resonance studies on the longitudinal $(T_1)$ and transverse $(T_2)$ relaxation times of phosphorus donors in bulk silicon with various electric field strengths up to near avalanche breakdown in high magnetic fields of about 1.2 T and low temperatures of about 8 K. We fi…
Upgraded metallurgical-grade (UMG) Si is obtained via a purification route alternative to the one used for conventional polysilicon and with significantly reduced environmental impact. Additionally, despite a lower purity level in the feedstock than polysilicon, UMG-Si has demonstrated potential for the fabrication of highly efficient and low-cost solar cells. Low initial bulk carrier lifetimes recorded in UMG-Si bare wafers can be improved by means of an adequate Phosphorus Diffusion Gettering (PDG) process to the level of mc-Si. In this letter, optimized PDG processes for UMG-Si are reported…
Light-emitting diodes (LEDs) based on III-V/II-VI materials have delivered a compelling performance in the mid-infrared (mid-IR) region, which enabled wide-ranging applications, including environmental monitoring, defense and medical diagnostics. Continued efforts are underway to realize on-chip sensors via heterogeneous integration of mid-IR emitters on a silicon photonic chip. But the uptake of such approach is limited by the high costs and interfacial strains, associated with the process of heterogeneous integrations. Here, the black phosphorus (BP)-based van der Waals (vdW) heterostructure…
This work reports the measurement of electron $g$ factor anisotropy ($| Δg |$ = $| g_{001} - g_{1 \bar 1 0} |$) for phosphorous donor qubits in strained silicon (sSi = Si/Si$_{1-x}$Ge$_x$) environments. Multi-million-atom tight-binding simulations are performed to understand the measured decrease in $| Δg |$ as a function of $x$, which is attributed to a reduction in the interface-related anisotropy. For $x <$7\%, the variation in $| Δg |$ is linear and can be described by $η_x x$, where $η_x \approx$1.62$\times$ 10$^{-3}$. At $x$=20\%, the measured $| Δg |$ is 1.2 $\pm$ 0.04 $\times$ 10$^{-3}…
Excitations of impurity complexes in semiconductors can not only provide a route to fill the terahertz gap in optical technologies, but can also connect local quantum bits to scale up solid-state quantum-computing devices. However, taking into account both the interactions among electrons/holes, and the host band structures, is challenging. Here we combine first-principles band-structure calculations with quantum-chemistry methodology to evaluate the ground and excited states of a pair of phosphorous donors in silicon within s single framework. We use a broken-symmetry Hartree-Fock approach, f…
Direct visualizations of spin accumulation due to the enhanced spin Hall effect (SHE) in bismuth (Bi) - doped silicon (Si) at room temperature are realized by using helicity-dependent photovoltage (HDP) measurements. Under application of a dc current to the Bi-doped Si, clear helicity-dependent photovoltages are detected at the edges of the Si channel, indicating a perpendicular spin accumulation due to the SHE. In contrast, the HDP signals are negligibly small for phosphorus-doped Si. Compared to a platinum channel, which has a large spin Hall angle, more than two-orders of magnitude larger H…
High-field Overhauser DNP in silicon below the metal-insulator transition
单晶硅是探索动态核极化（DNP）的优秀系统，因为它表现出作为掺杂浓度和温度的函数的从金属到绝缘的连续性质。在低掺杂浓度下，已经观察到DNP通过固体效应发生，而在非常高的掺杂浓度下，奥弗豪泽机制负责。在这里，我们报告了n型掺杂硅晶体中29 Si的超极化，掺杂浓度范围为1-3 x 10^17 /cc。在这种制度下，捐助者之间的交流互动变得极其重要。在我们的实验中的增强的迹象和它的频率依赖性表明，29 Si的自旋直接极化的施主电子通过交换耦合施主集群内的Overhauser机制。供体之间的交换相互作用仅需要大于硅超精细相互作用（通常比供体超精细耦合小得多）以实现该奥弗豪瑟机制。核极化增强观察到的范围内的捐助者集群中的交换能量是可比的捐助者超精细相互作用。的DNP动力学的特征在于由一个单一的指数时间常数，取决于微波功率，表明Overhauser机制是限速步骤。由于只有大约2%的硅核位于施主电子的一个玻尔半径内，核自旋扩散在将极化转移到所有自旋中是重要的。然而，由于相对较弱的硅超精细耦合强度，自旋扩散时间比奥弗豪瑟时间短得多。在2.35 T磁场和1.1 K下，我们观察到微波辐射两小时后$244 +/- 84 resulting in a silicon polarization of $ 10.4 +/-3.4%的DNP增强.
Nuclear spin polarization in silicon carbide at room temperature in the Earth's magnetic field
Helmholtz-Zentrum Dresden-Rossendorf（亥姆霍兹德累斯顿-罗斯多夫中心）；ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology（ICFO光子科学研究所，巴塞罗那科技研究院）
