Extremely high electron mobility in isotopically-enriched 28Si two-dimensional electron gases grown by chemical vapor deposition

Li, Jiun-Yun; Huang, Chiao-Ti; Rokhinson, Leonid P.; Sturm, James C.

doi:10.1063/1.4824729

Cited by 25 publications

(21 citation statements)

References 14 publications

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“…Isotopically enriched, strained 28 Si thin layers were grown by solid-source molecular beam epitaxy (MBE) at the Technical University of Munich (TUM), Germany [42] and by CVD at Princeton University, USA. [43] Some electron doublequantum dots were fabricated using the strained silicon. [44] Other isotopically controlled silicon low-dimensional structures, typically grown by MBE, [45][46][47][48] have been employed, predominantly for diffusion [49][50][51][52] and amorphization [53] studies.…”

Section: Silicon Quantum Computationmentioning

confidence: 99%

Isotope engineering of silicon and diamond for quantum computing and sensing applications

2014

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Some of the stable isotopes of silicon and carbon have zero nuclear spin, whereas many of the other elements that constitute semiconductors consist entirely of stable isotopes that have nuclear spins. Silicon and diamond crystals composed of nuclear-spin-free stable isotopes ( 28 Si, 30 Si, or 12 C) are considered to be ideal host matrixes to place spin quantum bits (qubits) for quantum-computing and -sensing applications, because their coherent properties are not disrupted thanks to the absence of host nuclear spins. The present paper describes the state-of-theart and future perspective of silicon and diamond isotope engineering for development of quantum information-processing devices.

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Section: Silicon Quantum Computationmentioning

confidence: 99%

Isotope engineering of silicon and diamond for quantum computing and sensing applications

2014

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“…A common approach to experimentally determine the dominant scattering mechanisms in two-dimensional systems is to extract the power-law exponent from the density dependence of the mobility. Several experimental and theoretical studies have used similar techniques to analyze disorder in GaAs/AlGaAs structures, [15][16][17][18][19][20][21] Si MOSFETs, 22 and doped 4,[23][24][25] and undoped [26][27][28] Si/SiGe heterostructures. With this in mind, we present in this work a systematic study of the depth dependence of scattering mechanisms in undoped shallow Si/SiGe quantum wells with channel depth ranging from 100 nm to only 10 nm away from the surface, the shallowest Si/SiGe device reported to date.…”

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Scattering mechanisms in shallow undoped Si/SiGe quantum wells

et al. 2015

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We report the magneto-transport study and scattering mechanism analysis of a series of increasingly shallow Si/SiGe quantum wells with depth ranging from ∼ 100 nm to ∼ 10 nm away from the heterostructure surface. The peak mobility increases with depth, suggesting that charge centers near the oxide/semiconductor interface are the dominant scattering source. The power-law exponent of the electron mobility versus density curve, μ ∝ nα, is extracted as a function of the depth of the Si quantum well. At intermediate densities, the power-law dependence is characterized by α ∼ 2.3. At the highest achievable densities in the quantum wells buried at intermediate depth, an exponent α ∼ 5 is observed. We propose and show by simulations that this increase in the mobility dependence on the density can be explained by a non-equilibrium model where trapped electrons smooth out the potential landscape seen by the two-dimensional electron gas.

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“…Ensemble spin resonance of 31 P donors in isotopically pure 28 Si has shown extraordinarily long coherence times, T 2e % 10 s for the electron 13 and T 2n % 3 h for the nucleus, 14 and it is certainly an exciting prospect to adopt isotopically pure substrates for nanoscale qubit devices. However, the production of nuclear spin-zero environments in isotopically purified semiconductors other than silicon is relatively undeveloped 15 or impossible because of the lack of suitable isotopes. Therefore, methods to maximize qubit control fidelities in the presence of a nuclear spin environment will remain important.…”

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High-fidelity adiabatic inversion of a ³¹P electron spin qubit in natural silicon

et al. 2014

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The main limitation to the high-fidelity quantum control of spins in semiconductors is the presence of strongly fluctuating fields arising from the nuclear spin bath of the host material. We demonstrate here a substantial improvement in single-qubit inversion fidelities for an electron spin qubit bound to a 31 P atom in natural silicon, by applying adiabatic sweeps instead of narrow-band pulses. We achieve an inversion fidelity of 97%, and we observe signatures in the spin resonance spectra and the spin coherence time that are consistent with the presence of an additional exchange-coupled donor. This work highlights the effectiveness of simple adiabatic inversion techniques for spin control in fluctuating environments. P donor electron 7 and nuclear 8 spins in silicon. In any III-V semiconductor, as well as in natural Si, the fluctuating nuclear spin environment is the main factor limiting spin coherence times 9,10 and, importantly, the fidelity of quantum gate operations, with typical fidelities in the range of 55%-75%. 4,7 This is insufficient for fault-tolerant qubit operations, which require fidelities in excess of 99% even in the most optimistic schemes.11 Group IV semiconductors such as Si and C possess spin-zero nuclear isotopes, which can be artificially enriched to create a nearly spin-free environment for spin qubits. Indeed 28 Si has been termed a "semiconductor vacuum" 12 for this reason. Ensemble spin resonance of 31 P donors in isotopically pure 28 Si has shown extraordinarily long coherence times, T 2e % 10 s for the electron 13 and T 2n % 3 h for the nucleus, 14 and it is certainly an exciting prospect to adopt isotopically pure substrates for nanoscale qubit devices. However, the production of nuclear spin-zero environments in isotopically purified semiconductors other than silicon is relatively undeveloped 15 or impossible because of the lack of suitable isotopes. Therefore, methods to maximize qubit control fidelities in the presence of a nuclear spin environment will remain important.In this Letter, we present how adiabatic frequency sweeps can be utilized to control the spin of an electron bound to a single 31 P donor with high-fidelity, in spite of the fluctuating nuclear spins from the 4.7% 29 Si (spin 1/2) in natural silicon. For an inhomogeneously broadened electron spin resonance (ESR) transition at $36 GHz with a linewidth of $12 MHz, we achieved an average electron spin inversion fidelity as high as F I ¼ 97 6 2%, insensitive to fluctuations of the background nuclear field. The method of adiabatic passage has been widely applied in nuclear magnetic resonance 16 and to some extent also in ESR. 17 Recent progress in high-frequency electronics and the very active research field of spin-based quantum computation have reignited the interest in this topic, with applications as ultra-wideband inversion, 18 geometric phase gates, 19 and even the inversion of single electron spins in diamond. 20,21 Our single qubit, however, is operated at much higher frequencies (36 GHz in the present work) t...

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Extremely high electron mobility in isotopically-enriched 28Si two-dimensional electron gases grown by chemical vapor deposition

Abstract: Articles you may be interested inExperimental and theoretical analysis of the temperature dependence of the two-dimensional electron mobility in a strained Si quantum well

Cited by 25 publications

References 14 publications

Isotope engineering of silicon and diamond for quantum computing and sensing applications

Isotope engineering of silicon and diamond for quantum computing and sensing applications

Scattering mechanisms in shallow undoped Si/SiGe quantum wells

High-fidelity adiabatic inversion of a ³¹P electron spin qubit in natural silicon

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Extremely high electron mobility in isotopically-enriched 28Si two-dimensional electron gases grown by chemical vapor deposition

Abstract: Articles you may be interested inExperimental and theoretical analysis of the temperature dependence of the two-dimensional electron mobility in a strained Si quantum well

Cited by 25 publications

References 14 publications

Isotope engineering of silicon and diamond for quantum computing and sensing applications

Isotope engineering of silicon and diamond for quantum computing and sensing applications

Scattering mechanisms in shallow undoped Si/SiGe quantum wells

High-fidelity adiabatic inversion of a 31P electron spin qubit in natural silicon

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High-fidelity adiabatic inversion of a ³¹P electron spin qubit in natural silicon