Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userContact resistance of various metallisation schemes to superconducting boron doped diamond between 1.9 and 300 K
214
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Diamond is a material that offers potential in numerous device applications. In particular, highly boron doped diamond is attractive due to its superconductivity and high Youngs Modulus. The fabrication of stable, low resistance, ohmic contacts is essential to ensure proper device function. Previous work has established the efficacy of several methods of forming suitable contacts to diamond at room temperature and above, including carbide forming and carbon soluble metallisation schemes. Herein, the stability of several contact schemes (Ti, Cr, Mo, Ta and Pd) to highly boron doped nanocrystalline diamond was verified down to the cryogenic temperatures with modified Transmission Line Model (TLM) measurements. While all contact schemes remained ohmic, a significant temperature dependency is noted at Tc and at the lowest temperatures the contact resistances ranged from Ti/Pt/Au with ${(8.83 pm 0.10)times 10^{-4} :{Omega}.cm}$ to Ta/Pt/Au with ${(8.07 pm 0.62) times 10^{-6} :{Omega}.cm}$.
rate research
Read More
This work investigates the high-pressure structure of freestanding superconducting ($T_{c}$ = 4.3,K) boron doped diamond (BDD) and how it affects the electronic and vibrational properties using Raman spectroscopy and x-ray diffraction in the 0-30,GPa range. High-pressure Raman scattering experiments revealed an abrupt change in the linear pressure coefficients and the grain boundary components undergo an irreversible phase change at 14,GPa. We show that the blue shift in the pressure-dependent vibrational modes correlates with the negative pressure coefficient of $T_{c}$ in BDD. The analysis of x-ray diffraction data determines the equation of state of the BDD film, revealing a high bulk modulus of $B_{0}$=510$pm$28,GPa. The comparative analysis of high-pressure data clarified that the sp$^{2}$ carbons in the grain boundaries transform into hexagonal diamond.
Boron-doped diamond granular thin films are known to exhibit superconductivity with an optimal critical temperature of Tc = 7.2K. Here we report the measured complex surface impedance of Boron-doped diamond films in the microwave frequency range using a resonant technique. Experimentally measured inductance values are in good agreement with estimates obtained from the normal state sheet resistance of the material. The magnetic penetration depth temperature dependence is consistent with that of a fully-gapped s-wave superconductor. Boron-doped diamond films should find application where high kinetic inductance is needed, such as microwave kinetic inductance detectors and quantum impedance devices.
We report a study of the relaxation time of the restoration of the resistive superconducting state in single crystalline boron-doped diamond using amplitude-modulated absorption of (sub-)THz radiation (AMAR). The films grown on an insulating diamond substrate have a low carrier density of about 2.5x10^{21} cm^{-3} and a critical temperature of about 2 K. By changing the modulation frequency we find a high-frequency rolloff which we associate with the characterstic time of energy relaxation between the electron and the phonon systems or the relaxation time for nonequilibrium superconductivity. Our main result is that the electron-phonon scattering time varies clearly as T^{-2}, over the accessible temperature range of 1.7 to 2.2 K. In addition, we find, upon approaching the critical temperature T_c, evidence for an increasing relaxation time on both sides of T_c.
Diamond is an excellent band insulator. However, boron (B) doping is known to induce superconductivity. We present two interesting effects in superconducting B doped diamond (BDD) thin films: i) Wohlleben effect (paramagnetic Meissner effect, PME) and ii) a low field spin glass like susceptibility anomaly. We have performed electrical and magnetic measurements (under pressure in one sample) at dopings (1.4 , 2.6 and 3.6) X 1021 cm-3, in a temperature range 2 - 10 K. PME, a low field anomaly in inhomogeneous superconductors could arise from flux trapping, flux compression, or for non-trivial reason such as emergent Josephson Pi junctions. Joint occurrence of PME and spin glass type anomalies points to possible emergence of Pi junctions. BDD is a disordered s-wave superconductor; and Pi junctions could be produced by spin flip scattering of spin half moments when present at weak superconducting regions (Bulaevski et al. 1978). A frustrated network of 0 and Pi junctions will result (Kusmartsev et al. 1992) in a distribution of spontaneous equilibrium supercurrents, a phase glass state. Anderson localized spin half spinons embedded in a metallic fluid (two fluid model of Bhatt et al.) could create Pi junction by spin flip scattering. Our findings are consistent with presence of Pi junctions, invoked to explain their (Bhattacharyya et al.) observation of certain resistance anomaly in BDD.
Superconductivity of boron-doped diamond, reported recently at T_c=4 K, is investigated exploiting its electronic and vibrational analogies to MgB2. The deformation potential of the hole states arising from the C-C bond stretch mode is 60% larger than the corresponding quantity in MgB2 that drives its high Tc, leading to very large electron-phonon matrix elements. The calculated coupling strength lambda ~ 0.5 leads to T_c in the 5-10 K range and makes phonon coupling the likely mechanism. Higher doping should increase T_c somewhat, but effects of three dimensionality primarily on the density of states keep doped diamond from having a T_c closer to that of MgB2.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
