The new high field photoexcitation muon spectrometer at the ISIS pulsed neutron and muon source

Yokoyama, Koji; Lord, J. S.; Murahari, Prashantha; Wang, K.; Dunstan, D. J.; Waller, S.; McPhail, D.; Hillier, A. D.; Henson, J.; Harper, M. R.; Heathcote, Peter; Drew, Alan J.

doi:10.1063/1.4972827

Cited by 14 publications

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“…As the peristaltic pump circulates the sample liquid, the spiral thermalises the temperature of the liquid before it reaches the sample holder, minimizing sample temperature perturbations as the liquid circulates. This is particularly important when the sample is continuously circulated during an experiment, and it has previously been demonstrated as an effective solution for this type of sample flow system [29]. This configuration therefore enables measurements to be carried out in two different regimes: firstly, with a static liquid sample, which is achieved by isolating the liquid circuit after filling the sample cell, and secondly, with a liquid sample under continuous circulation.…”

Section: Insert Developmentmentioning

confidence: 99%

Next generation equipment for muon chemistry research

Aramini

Cottrell

Peck

et al. 2020

JNR

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Muon spectroscopy offers a uniquely sensitive method for exploring many mechanisms in chemistry and chemical physics through the study of muonium, a probe species formed during muon implantation that is chemically equivalent to hydrogen. Next generation experiments in the field of muonium chemistry will require reliable liquid handling systems, in-situ experimental capabilities and access to advanced methods such as Radio-Frequency (RF) muon spin resonance spectroscopy. This paper discusses the development and commissioning of systems for sample handling, describing details of two liquid panels suitable for deoxygenation and transfer of liquid samples, the development of a centre stick for an existing 4 He flow cryostat suitable for RF muon chemistry experiments, a dedicated muon chemistry insert specifically optimized for RF liquid phase chemistry experiments, and a birdcage RF cavity optimized for high frequency measurements and with a geometry wellsuited for beamline experiments that exploit the chemistry insert. Example data is presented, demonstrating the application of these various pieces of equipment.

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Section: Insert Developmentmentioning

confidence: 99%

Next generation equipment for muon chemistry research

Aramini

Cottrell

Peck

et al. 2020

JNR

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“…In a case of single crystal Si, the implantation depth can be as deep as 700 µm, where the surface effect is negligibly small in most cases. Our recent upgrade of the HiFi muon spectrometer at the ISIS pulsed neutron and muon source in the UK enables us to photoexcite samples with a high-energy laser pulse [7][8][9]. A pulsed muon source is useful for timedifferential studies, as well as for achieving a large stimulation by virtue of the high-intensity light source.…”

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confidence: 99%

“…A pulsed muon source is useful for timedifferential studies, as well as for achieving a large stimulation by virtue of the high-intensity light source. The sample temperature can be varied in a wide range using cryostats and hot stages available in the HiFi experimental suite [7,10]. Combining these capabilities, muon spin spectroscopy (collectively known as µSR, corresponding to muon spin relaxation/rotation/resonance) can not only measure the excess carrier lifetime but also investigate its injection and temperature dependence.…”

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confidence: 99%

“…1 incoming pump light, whereas the other side faces the muon beam. Details of the experimental setup, including the sample environment, are explained elsewhere [7]. The distribution of stopped muon is centered in the wafer by adjusting the number of aluminum foil degraders, with its FWHM estimated to be ≈130 µm by a Monte Carlo simulation.…”

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confidence: 99%

“…1(b) illustrates the pulse timing, in which muon pulses arrive at the sample at ∆T after laser pulses. Since the repetition rate of laser and muon are 25 and (pseudo-)50 Hz respectively [7], the muon data are sorted and binned to "light ON" and "light OFF" spectra, and averaged for statistics, assuming that the photoinduced change is already over after 20 ms. In the optical setup, two attenuator assemblies and calibrated neutral density filters are used to control the pump laser energy accurately for a wide range of carrier injection.…”

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Photoexcited Muon Spin Spectroscopy: A New Method for Measuring Excess Carrier Lifetime in Bulk Silicon

et al. 2017

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We have measured the optically injected excess carrier lifetime in silicon using photoexcited muon spin spectroscopy. Positive muons implanted deep in a wafer can interact with the excess carriers and directly probe the bulk carrier lifetime whilst minimizing the effect from surface recombination. The method is based on the relaxation rate of muon spin asymmetry, which depends on the excess carrier concentration. The underlying microscopic mechanism has been understood by simulating the fourstate muonium model in Si under illumination. We apply the technique to different injection levels and temperatures, and demonstrate its ability for injection-and temperature-dependent lifetime spectroscopy.Excess carrier lifetime in semiconductors is an extremely sensitive probe of recombination active defect density N t [1,2]. In the case of silicon, a lifetime spectroscopy can probe N t as low as 10 10 cm −3 , corresponding to the carrier lifetime in the order of 10 ms. Therefore the lifetime measurements have been utilized to test a quality of Si wafers in various areas, and especially appreciated in photovoltaic applications where the carrier lifetime is a key parameter for the excess carriers to successfully diffuse across the p-n junction in solar cells. The microchip industries have also found its use as a cleanliness monitor in the chip manufacturing processes. It is now widely accepted that there are three main mechanisms that cause the electron-hole pair (EHP) recombination in semiconductors: 1) Shockley-Read-Hall (SRH) recombination (characterized by its lifetime τ SRH ), 2) Auger recombination (τ Auger ), and 3) radiative recombination (τ rad ) [1,2]. The bulk recombination lifetime τ bulk is then given by a relation,Among those mechanisms, the SRH recombination is a multiphonon process mediated by deep-level defect centers, and dominates τ bulk in low-level carrier injections, whilst the Auger recombination plays a key role in highlevel injections. The radiative recombination is usually negligible in bulk Si due to the indirect band structure. Although τ SRH gives a good indication of the N t level, it alone cannot determine N t explicitly -it is always necessary to assume the defect type, which is characterized by its energy level and capture cross section for electrons and holes. To measure the carrier lifetime, there are several traditional and novel methods, such as the photoconductance decay (PCD) and photoluminescence decay measurements. Induction-coupled PCD and its varieties are becoming more popular by virtue of their contactless and non-destructive measurement [1,2,6]. These techniques measure, by their nature, the effective lifetime of injected carriers, given by 1/τ ef f = 1/τ bulk + 1/τ S . The second term represents a contribution from the surface lifetime τ S which strongly depends on how the wafer surface has been conditioned. It is therefore necessary to extract τ bulk by 1) treating the surface to make τ S asymptote either 0 (e.g. sandblasting) or ∞ (e.g. passivation), or 2) measuring the same ...

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The $$ \mu $$SR Technique

Amato,

Morenzoni

2024

Lecture Notes in Physics

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The new high field photoexcitation muon spectrometer at the ISIS pulsed neutron and muon source

Cited by 14 publications

References 34 publications

Next generation equipment for muon chemistry research

Next generation equipment for muon chemistry research

Photoexcited Muon Spin Spectroscopy: A New Method for Measuring Excess Carrier Lifetime in Bulk Silicon

The $$ \mu $$SR Technique

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