ZERO-BIAS ANOMALIES IN THE CURRENT-VOLTAGE AND CONDUCTANCE-VOLTAGE CHARACTERISTICS OF HIGH-CRITICAL-TEMPERATURE SUPERCONDUCTOR JUNCTIONS

1992 ◽  
Vol 06 (02) ◽  
pp. 125-170 ◽  
Author(s):  
THOMAS WALSH
Keyword(s):  
Critical Temperature ◽  
Proximity Effects ◽  
High Critical Temperature ◽  
Normal Surface ◽  
Superconducting Layer ◽  
Zero Bias ◽  
Current Voltage ◽  
Conductive Channel ◽  
In Series ◽  
Magnetic States

The occurrence of zero-bias anomalies (ZBAs) in the current-voltage and conductance-voltage characteristics of high-critical-temperature superconductors (HTS) is reviewed. Following a historical introduction, we summarize studies noting HTS ZBAs. Several explanations of the ZBAs in HTS tunneling characteristics have been proposed including a resistance in series with a Josephson junction, a conductive channel near the Fermi energy ε F , localized magnetic states on film surfaces, proximity effects, a peak in the electron density of states near ε F , an array of junctions in an HTS ceramic sample, coupling between a film's normal surface layer and the superconducting layer below the surface, quasiparticle tunneling, and phase diffusion. The plausibility and implications of these suggested explanations are discussed. Experiments to answer questions that remain regarding the source and significance of the ZBAs are proposed.

ANALYSIS OF AC TRANSPORT MEASUREMENTS ON GDSR2RUCU2O8

2003 ◽  
Vol 17 (04n06) ◽  
pp. 910-915 ◽  
Author(s):  
A. VECCHIONE ◽  
D. ZOLA ◽  
C. NOCE ◽  
G. CARAPELLA ◽  
M. GOMBOS ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Curie Temperature ◽  
Temperature Dependence ◽  
Phenomenological Model ◽  
Low Frequency ◽  
Onset Temperature ◽  
Transport Measurements ◽  
Current Voltage ◽  
In Series ◽  
Physical Quantities

Low frequency transport measurements have been performed on GdSr 2 RuCu 2 O 8 pellets. The current-voltage curves measured show an irreversible behavior in whole range of temperature explored. From these curve a Curie temperature TcM=133 K and a superconducting critical temperature TcS = 14 K , with an onset temperature TcO=33 K , have been deduced. A simple phenomenological model assuming a non-linear inductance in series with a resistance has been proposed to explain experimental current-voltage curves. Within this model, the temperature dependence of some physical quantities has been also investigated.

The Deposition, Fabrication and Characteristics of High Critical Temperature Devices

1987 ◽  
Vol 99 ◽  
Author(s):  
G. W. Morris ◽  
M. G. Blamire ◽  
R. E. Somekh ◽  
E. J. Tomlinson ◽  
J. E. Evetts
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Critical Temperature ◽  
Heat Treatments ◽  
Sputter Deposition ◽  
High Critical Temperature ◽  
The Third ◽  
Current Voltage ◽  
Device Structures ◽  
Temperature Heat

ABSTRACTIn the first section of this paper the sputter deposition of thin films of YBa2Cu3O7−x is considered. In the second section low and high temperature heat treatments are discussed in the light of the thermodynamics of the material and in the third the development, fabrication and current-voltage (IV) characteristics of a variety of device structures are described, including the hysterctic characteristics of certain YBa2Cu3O7−x / YBa2Cu3O7−x devices that reveal Josephson supcrcurrcnt tunnelling.

scholarly journals Correlation between Defects and Electrical Performances of Ion-Irradiated 4H-SiC p–n Junctions

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1966
Author(s):  
Domenico Pellegrino ◽  
Lucia Calcagno ◽  
Massimo Zimbone ◽  
Salvatore Di Franco ◽  
Antonella Sciuto
Keyword(s):  
Deep Level ◽  
Electrical Characterization ◽  
High Fluence ◽  
Defect States ◽  
Exponential Parameter ◽  
Current Voltage ◽  
Different Temperatures ◽  
In Series ◽  
Transient Spectroscopy ◽  
Fluence Range

In this study, 4H-SiC p–n junctions were irradiated with 700 keV He+ ions in the fluence range 1.0 × 1012 to 1.0 × 1015 ions/cm2. The effects of irradiation were investigated by current–voltage (I–V) and capacitance–voltage (C–V) measurements, while deep-level transient spectroscopy (DLTS) was used to study the traps introduced by irradiation defects. Modifications of the device’s electrical performances were observed after irradiation, and two fluence regimes were identified. In the low fluence range (≤1013 ions/cm2), I–V characteristics evidenced an increase in series resistance, which can be associated with the decrease in the dopant concentration, as also denoted by C–V measurements. In addition, the pre-exponential parameter of junction generation current increased with fluence due to the increase in point defect concentration. The main produced defect states were the Z1/2, RD1/2, and EH6/7 centers, whose concentrations increased with fluence. At high fluence (>1013 ions/cm2), I–V curves showed a strong decrease in the generation current, while DLTS evidenced a rearrangement of defects. The detailed electrical characterization of the p–n junction performed at different temperatures highlights the existence of conduction paths with peculiar electrical properties introduced by high fluence irradiation. The results suggest the formation of localized highly resistive regions (realized by agglomeration of point defects) in parallel with the main junction.

Two dimensional CrGa2Se4: A spin-gapless ferromagnetic semiconductor with inclined uniaxial anisotropy

Nanoscale ◽  
2021 ◽  
Author(s):  
Qian Chen ◽  
Ruqian Wang ◽  
Zhaocong Huang ◽  
Shijun Yuan ◽  
Haowei Wang ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Material Science ◽  
2D Materials ◽  
Uniaxial Anisotropy ◽  
Magnetic Semiconductor ◽  
Ferromagnetic Semiconductor ◽  
Two Dimensional ◽  
High Critical Temperature

The magnetic semiconductor with high critical temperature has long been the focus in material science and recently is also known as one of the fundamental questions in two-dimensional (2D) materials....

A Self-Doped Oxygen-Free High-Critical-Temperature (High-Tc) Superconductor: SmFFeAs

2019 ◽  
Vol 58 (22) ◽  
pp. 15401-15409 ◽  
Author(s):  
Dan Lin ◽  
Han-Shu Xu ◽  
Jingjing Luo ◽  
Haoliang Huang ◽  
Yalin Lu ◽  
...  
Keyword(s):  
Critical Temperature ◽  
High Critical Temperature ◽  
High Tc ◽  
High Tc Superconductor

Metal Contacts on a-GaN

1996 ◽  
Vol 1 ◽  
Author(s):  
T. U. Kampen ◽  
W. Mönch
Keyword(s):  
Tight Binding ◽  
Image Force ◽  
Schottky Contacts ◽  
Metal Contacts ◽  
Zero Bias ◽  
Barrier Heights ◽  
Current Voltage ◽  
Optical Dielectric Constant ◽  
Optical Dielectric ◽  
Gap States

The Schottky barrier heights of silver and lead contacts on n-type GaN (0001) epilayers were determined from current-voltage characteristics. The zero-bias barrier heights and the ideality factors were found to be linearly correlated. Similar observations were previously reported for metal contacts on Si (111) and GaAs (110) surfaces. The barrier heights of ideal Schottky contacts are characterized by image force lowering of the barrier only. This gives an ideality factor of 1.01. From our data we obtain barrier heights of 0.82 eV and 0.73eV for ideal Ag and Pb contacts on GaN, respectively. The metal-induced gap states (MIGS) model predicts the barrier heights of ideal Schottky contacts on a given semiconductor to be linearly correlated with the electronegativities of the metals. The two important parameters of this MIGS-and-electronegativity model are the charge neutrality level (CNL) of the MIGS and a slope parameter. The CNL may be calculated from the dielectric band gap and using the empirical tight-binding method. The slope parameters are given by the optical dielectric constant of the respective semiconductor. The predictions of the MIGS model for metal/GaN contacts are confirmed by the results presented here and by barrier heights previously reported by others for Au, Ti, Pt, and Pd contacts on GaN.

Characterisation of high-critical temperature superconducting materials by ICP-AES technique

1992 ◽  
Vol 342 (4-5) ◽  
pp. 367-369 ◽  
Author(s):  
Madhuri J. Kulkarni ◽  
Aparna A. Argekar ◽  
S. K. Thulasidas ◽  
A. G. Page ◽  
M. D. Sastry
Keyword(s):  
Critical Temperature ◽  
Superconducting Materials ◽  
High Critical Temperature
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