Pick-up Transfer Research Articles

High mobility hydrogen-terminated diamond FET with h-BN gate dielectric using pickup method

Hydrogen-terminated diamond surfaces, emerging as a promising two-dimensional (2D) electron platform with great thermal and electronic properties, hold great potential for the next-generation high power and high frequency field effect transistor (FET). However, ideal gate dielectrics with high crystallinity and defect-free surfaces are still largely elusive. In this work, using the contamination-free pickup transfer method, hexagonal boron nitride (h-BN) flakes were fabricated on top of the hydrogen-terminated diamond surface to serve as a gate material and the passivation layer. The morphological and optical characterizations revealed the formation of homogeneous and intimate interface between h-BN and diamond. Benefiting from the h-BN gate dielectric layer, the maximum drain current density, subthreshold swing, and on/off ratio of diamond FET are measured to be −210.3 mA mm−1, 161 mV/dec, and 106, respectively. Especially, the transport measurement shows an almost constant Hall mobility of around 260 cm2 V−1 s−1 in the hole density range of 2 − 6 × 1012 cm−2, suggesting the excellent gate controllability of h-BN. Our results indicate that h-BN could form high-quality interface with hydrogen-terminated diamond, paving the way for the development of diamond-based electronic applications.

Technological Breakthroughs in Chip Fabrication, Transfer, and Color Conversion for High-Performance Micro-LED Displays.

The implementation of high-efficiency and high-resolution displays has been the focus of considerable research interest. Recently, micro light-emitting diodes (micro-LEDs), which are inorganic light-emitting diodes of size <100 µm2 , have emerged as a promising display technology owing to their superior features and advantages over other displays like liquid crystal displays and organic light-emitting diodes. Although many companies have introduced micro-LED displays since 2012, obstacles to mass production still exist. Three major challenges, i.e., low quantum efficiency, time-consuming transfer, and complex color conversion, have been overcome with technological breakthroughs to realize cost-effective micro-LED displays. In the review, methods for improving the degraded quantum efficiency of GaN-based micro-LEDs induced by the size effect are examined, including wet chemical treatment, passivation layer adoption, LED structure design, and growing LEDs in self-passivated structures. Novel transfer technologies, including pick-up transfer and self-assembly methods, for developing large-area micro-LED displays with high yield and reliability are discussed in depth. Quantum dots as color conversion materials for high color purity, and deposition methods such as electrohydrodynamic jet printing or contact printing on micro-LEDs are also addressed. This review presents current status and critical challenges of micro-LED technology and promising technical breakthroughs for commercialization of high-performance displays.

Investigation of the transfer reactions induced by 16O in 27Al and 28Si at Elab = 240 MeV

In this contribution, we present first experimental results for the deuteron pickup transfer in the 16O+28Si system at E lab. = 240 MeV. This reaction populates states in the 26Al target-like nucleus. In the same experimental campaign we have also measured the one-proton transfer 28Si(16O,17F)27Al and one-neutron transfer 27Al(16O,17O)26Al at the same beam energy. Comparison between the energy spectrum of these transfer reactions indicate that: i) the one-proton and one-neutron transfers favor the population of the low-lying states; ii) deuteron transfer to the ground state in 26Al is highly suppressed; iii) the cross-sections for deuteron transfer that populates low-lying states in 26Al are roughly 3 times less than the one-neutron transfer.

Fusion and back-angle quasielastic measurements in Si30+Gd156 near the Coulomb barrier

Background: Advancement in accelerator facilities has opened the door to dig deep to understand the interplay between nuclear reactions and structures. Although the influence of inelastic excitations on nuclear scattering and sub-barrier fusion is somewhat established, a clear understanding of nucleon transfer with a positive-$Q$ value is yet to achieve.Purpose: The objective of this paper is to examine the role of the $2n$-transfer channel with a positive $Q$ value on sub-barrier fusion and back-angle quasielastic (QE) scattering in the $^{30}\mathrm{Si}+^{156}\mathrm{Gd}$ reaction. Furthermore, extraction of barrier distributions (BDs) from fusion and QE scattering to infer their shapes is also a prime goal.Method: The excitation functions (EFs) of fusion and back-angle QE scattering have been measured over a wide range of incident beam energy around the Coulomb barrier using a recoil mass spectrometer. Furthermore, BDs have been extracted using the measured fusion and back-scattered QE data. The underlying findings have been analyzed within the framework of coupled-channel (CC) formalism using ccfull and ecc programs.Results: Fusion enhancement has been observed compared to those predicted from the one-dimensional barrier penetration model at sub-barrier energies. Fusion enhancement and QE EFs are explained by CC predictions considering the collective excitations among the colliding nuclei. The inclusion of $2n$ transfer and collective excitations in ccfull improves the fit to the experimental fusion data in a short span of energy window around the Coulomb barrier, whereas no significant effect has been observed at the sub-barrier region. However, no such effect of $2n$-pickup transfer has been observed from ecc model calculations. Thus, no firm conclusion can be made on the role of $2n$-pickup transfer with a positive $Q$ value in present measurements.Conclusion: Fusion EFs have been successfully explained by the CC calculations using ccfull and ecc model codes. No significant effect of the $2n$-pickup channel with a positive $Q$ value was observed on sub-barrier fusion enhancement. However, QE EFs are reproduced by considering the collective excitations and $2n$-transfer channel couplings. Fusion and QE BDs are similar in shape within the experimental uncertainty. One-dimensional barrier parameters extracted from the measured data agree with the different theoretical models. Also, the present system obeys the systematic based on deformation values after transfer at the exit.

Evaluation of the K35(p,γ)Ca36 reaction rate using the Ca37(p,d)Ca36 transfer reaction

Background: A recent sensitivity study has shown that the K35(p,γ)Ca36 reaction is one of the ten (p,γ) reaction rates that could significantly impact the shape of the calculated x-ray burst light curve. Its reaction rate used up to now in type I x-ray burst calculations was estimated using an old measurement for the mass of Ca36 and theoretical predictions for the partial decay widths of the first 2+ resonance with arbitrary uncertainties. Purpose: In this work, we propose to reinvestigate the K35(p,γ)Ca36 reaction rate, as well as related uncertainties, by determining the energies and decay branching ratios of Ca36 levels, within the Gamow window of x-ray bursts, in the 0.5 to 2 GK temperature range. Method: These properties were studied by means of the one-neutron pickup transfer reaction Ca37(p,d)Ca36 in inverse kinematics using a radioactive beam of Ca37 at 48 MeV nucleon−1. The experiment was performed at the GANIL facility using the liquid hydrogen target CRYPTA, the MUST2 charged particle detector array for the detection of the light charged particles, and a zero degree detection system for the outgoing heavy recoil nuclei. Results: The atomic mass of Ca36 is confirmed and new resonances have been proposed together with their proton decay branching ratios. This spectroscopic information, used in combination with very recent theoretical predictions for the γ-decay width, were used to calculate the K35(p,γ)Ca36 reaction rate. The recommended rate of the present work was obtained within a uncertainty factor of 2 at 1σ. This is consistent with the previous estimate in the x-ray burst temperature range. A large increase of the reaction rate was found at higher temperatures due to two newly discovered resonances. Conclusions: The K35(p,γ)Ca36 thermonuclear reaction rate is now well constrained by the present work in a broad range of temperatures covering those relevant to type I x-ray bursts. Our results show that the K35(p,γ)Ca36 reaction does not affect the shape of the x-ray burst light curve, and that it can be removed from the list of the few influential proton radiative captures reactions having a strong impact on the light curve.Received 18 January 2021Accepted 12 April 2021DOI:https://doi.org/10.1103/PhysRevC.103.055809©2021 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDirect reactionsExplosive burningNuclear astrophysicsNuclear physics of explosive environmentsNucleon induced nuclear reactionsProton emissionRadiative captureTransfer reactionsProperties20 ≤ A ≤ 38Nuclear PhysicsGravitation, Cosmology & Astrophysics

Analysis of two-proton transfer in the Ca40(O18,Ne20)Ar38 reaction at 270 MeV incident energy

Two-nucleon transfer reactions are essential tools to investigate specific features of the nuclear structure, such as the correlation among valence particles in the transfer process. Besides, transfer reactions may be an important channel to take into account in charge-exchange processes since they can represent a competing contribution to the final cross section. The two-proton pickup transfer reaction $^{40}\mathrm{Ca}(^{18}\mathrm{O},^{20}\mathrm{Ne})\phantom{\rule{0.16em}{0ex}}^{38}\mathrm{Ar}$ has been measured at 270 MeV, and the angular distributions for transitions to different excited states extracted. This paper shows the analysis of the data performed by finite-range coupled reaction channel and coupled-channel Born approximation methods. Extensive shell-model calculations are performed to derive the one- and two-proton spectroscopic amplitudes for the projectile and target overlaps. The role of the simultaneous and sequential two-proton transfer mechanisms to populate the measured final states or groups of states, mainly characterized by a high collectivity, is also discussed.

Understanding the mechanisms of nuclear collisions: A complete study of the B10+Sn120 reaction

Background: Reactions involving exotic and stable weakly bound nuclei have been extensively studied in recent years. Although several models have been successfully used to explain particular reaction outcomes, the answers to many questions remain elusive. In previous works, we presented elastic, inelastic, and transfer angular distributions for the $^{10}\mathrm{B}+^{120}\mathrm{Sn}$ system measured at ${E}_{\mathrm{Lab}}=31.5$, 33.0, 35.0, and 37.5 MeV. The data set was analyzed through coupled reaction channels calculations in the context of the double-folding S\~ao Paulo potential.Purpose: We investigate nuclear reaction mechanisms for systems involving weakly bound projectiles.Method: Angular distributions for several nuclear reaction processes were measured for the $^{10}\mathrm{B}+^{120}\mathrm{Sn}$ system at ${E}_{\mathrm{Lab}}=39.70$ MeV.Results: The new data set involves angular distributions for elastic scattering, projectile and target inelastic excitations, one-neutron pickup transfer, one-proton stripping transfer, deuteron pickup transfer, and $^{3,4}\mathrm{He}$ stripping transfer. We have also observed $^{10}\mathrm{Be}$ nuclei. The effect of the couplings to some nonelastic states on the angular distributions is discussed.Conclusion: The theoretical calculations within the coupled reaction channels formalism provide an overall good agreement with the corresponding inelastic, one-neutron stripping, one-proton pickup, one-deuteron pickup, and $^{3}\mathrm{He}$ stripping transfer data. However, to improve the description of the elastic scattering angular distribution, the inclusion of additional channels in the coupling scheme might be necessary.

Systematics of multinucleon transfer in heavy-ion reactions

One-neutron pickup reactions for 52 projectile–target combinations were analysed using a systematics between transfer cross-sections and ground-state Q-values. One-neutron pickup transfer shows a good correlation between reduced transfer cross-sections and ground-state Q-values ( $$Q_{gg}$$ ) if one separate the systems into two groups based on their $$Z_{p}Z_{t}$$ product. Also, similar kind of systematics is applied to 2n, 3n and 4n pickup transfer and a good correlation is obtained between reduced transfer cross-sections and $$Q_{gg}$$ values, where no $$Z_{p}Z_{t}$$ dependence is seen.

Investigation of the fusion process for B10+Au197 at near-barrier energies

In a previous work, we presented data for the $^{10}\mathrm{B}+^{197}\mathrm{Au}$ system, corresponding to quasielastic and elastic scattering, $^{197}\mathrm{Au}$ inelastic excitation, and one neutron pickup transfer, measuring the angular distribution of scattered beam-like ejectiles at several energies around the Coulomb barrier. In this paper, we present data for the fusion process of the same system, at several energies around the Coulomb barrier, as well as new data for one neutron pickup and stripping transfer. In this case, we detected offline $\ensuremath{\gamma}$ rays stemming from the $\ensuremath{\beta}$-delayed decay chain of fusion-evaporation residues and heavy transfer products. As in our previous work, we analyzed this data set with coupled reaction channels calculations using the S\~ao Paulo potential. We show that the coupling to the one neutron transfer channel is quite important to describe the fusion data at the sub-barrier energy region. We also provide a comparison of the experimental fusion cross sections obtained for $^{10}\mathrm{B}+^{197}\mathrm{Au}$ with data for several other systems involving the same target nucleus.

Scattering of O16,18 beams on Cu63,65 targets: A systematic study of different reaction channels

Precise quasielastic experimental excitation function for the $^{18}\mathrm{O}+^{65}\mathrm{Cu}$ system has been measured and its barrier distribution has been derived. Several reaction channels have been observed on the experimental spectra, revealing the presence of two-neutron and $\ensuremath{\alpha}$-stripping processes, as well as the proton pickup transfer, for which excitation functions were also measured. Extensive coupled channel and coupled reaction channel calculations have been performed to describe the experimental data. The inelastic couplings of target and projectile, and the ground state reorientation of the target, were important to the proper description of data. The transfer data were well described by calculations; however, it was shown that they almost do not affect the excitation function of $^{18}\mathrm{O}+^{65}\mathrm{Cu}$ quasielastic scattering. Whenever possible, structure shell model calculations have been performed to obtain the spectroscopic amplitudes of projectile and target overlaps. The two-neutron and $\ensuremath{\alpha}$-transfer reactions have been calculated considering the transferred particle as a cluster with spin 0.

Elastic scattering, inelastic excitation, and 1n pick-up transfer cross sections for B10 + Sn120 at energies near the Coulomb barrier

The $^{10}\mathrm{B}+^{120}\mathrm{Sn}$ reaction has been systematically studied at laboratory energies around the Coulomb barrier: ${E}_{\mathrm{LAB}}=31.5$, 33.5, 35.0, and 37.5 MeV. Cross sections for the elastic scattering and some reaction processes have been measured: excitation to the ${1}^{+}$ state of $^{10}\mathrm{B}$; excitation to the ${2}^{+}$ and ${3}^{\ensuremath{-}}$ states of $^{120}\mathrm{Sn}$; and the one-neutron pick-up transfer $^{120}\mathrm{Sn}(^{10}\mathrm{B},^{11}\mathrm{B})^{119}\mathrm{Sn}$. Coupled reaction channel (CRC) calculations have been performed in the context of the double-folding S\~ao Paulo potential. The theoretical calculations result in a good overall description of the experimental angular distributions. The effect on the theoretical elastic-scattering angular distributions of couplings to the inelastic and transfer states (through the CRC calculations) and to the continuum states (through continuum-discretized coupled-channels calculations) has been investigated.

Elastic, inelastic, and 1n transfer cross sections for the B10+Sn120 reaction

The $^{10}\mathrm{B}+^{120}\mathrm{Sn}$ reaction has been investigated at ${E}_{\mathrm{Lab}}=37.5$ MeV. The cross sections for different channels, such as the elastic scattering, the excitation of the ${2}^{+}$ and ${3}^{\ensuremath{-}}\phantom{\rule{4pt}{0ex}}^{120}\mathrm{Sn}$ states, the excitation of the ${1}^{+}$ state of $^{10}\mathrm{B}$, and the $1n$ pick-up transfer, have been measured. One-step distorted-wave Born approximation and coupled-reaction-channels calculations have been performed in the context of the double-folding S\~ao Paulo potential. The effect of coupling the inelastic and transfer states on the angular distributions is discussed in the paper. In general, the theoretical calculations within the coupled-reaction-channels formalism yield a satisfactory agreement with the corresponding experimental angular distributions.

Odd-even147−153Pm isotopes within the neutron-proton interacting boson-fermion model

Low-lying energy states of the ${}^{147\ensuremath{-}153}\text{Pm}$ isotopic chain are studied within the framework of the neutron-proton interacting boson-fermion model (IBFM-2). The spectra of these isotopes show a transition from a particle coupled to a vibrational core to a particle coupled to a deformed one. The calculation reproduces this behavior. In addition, reduced transition probabilities $B(E2)$ and $B(M1)$ and quadrupole and magnetic moments, as well as spectroscopic factors corresponding to stripping and pickup transfer reactions, are calculated. Obtained results compare well with the available experimental data, which reinforces the reliability of the wave functions obtained within the IBFM-2 model.

Depopulation of 180Tam by Coulomb excitation and possible astrophysical consequences.

The depopulation of [sup 180]Ta[sup [ital m]] by Coulomb excitation was investigated in a thick-target experiment using beams of [sup 32]S and [sup 36]S with energies of 70--130 MeV on disks of natural tantalum. The resulting [sup 180]Ta ground-state population was measured by detecting its eight-hour decay. At the higher incident energies the observed [sup 180]Ta yield is dominated by sub-Coulomb neutron pickup transfer reactions on the 10[sup 4] times more abundant [sup 181]Ta. At the lower incident energies in [sup 180]Ta ground-state yield is found to be compatible with Coulomb excitation of the isomer to an intermediate level with energies [ital E][sub [ital x]][lt]1 MeV and a reduced transition probability [ital B]([ital E]2)[congruent]0.02--0.25 Weisskopf units. Consequences for the astrophysical production mechanism of [sup 180]Ta are discussed.

Predictive power of supersymmetry in nuclear structure tested by pickup transfer reactions to 196Au.

Using the ${\mathrm{U}}_{\mathit{v}}$(6/12)\ifmmode\times\else\texttimes\fi{}${\mathrm{U}}_{\mathrm{\ensuremath{\pi}}}$(6/4) supersymmetry a prediction for the negative parity states in the odd-odd nucleus $^{196}\mathrm{Au}$ is obtained. Since almost no experimental knowledge existed on the excited states of $^{196}\mathrm{Au}$, the study of this nucleus is a stringent test for the predictive power of supersymmetry in nuclear structure. The theoretical values for the single-particle transfer reaction intensities from $^{197}\mathrm{Au}$ to $^{196}\mathrm{Au}$ are derived and compared with results of a high-resolution measurement of the $^{197}\mathrm{Au}$(d,t) and $^{197}\mathrm{Au}$${(}^{3}$He,\ensuremath{\alpha}) reactions.