Contact between High-T_c Superconductor and Semiconducting Niobium-Doped SrTiO₃

Abstract

Abstraci The recombinalion kinetics of photoinjected charge carriers in quasi-me-dimensional conducting polymers is studied. The dynamics of the correlated pair of photoexcitations is considered within Ihe model of one-dimensional diffusion of quasiparticles in segments of a polymer chain confined by defecls (traps). The main characteristics of the dynamics of a mmbining pair (disrribution function and survival prohability in a confined segment and the averaged survival probability in a polymer chain with random hap distribution) are calculated. The results obtained are associated with the observed characteristics, such as uansient phoUKunent decay, kinetics of photoinduced changes in optical absorption (or reflectivity) and delayed fluorescence caused by charge carrier recombination. It is shown thar the inRuence of the defects leads to acceleration of the photocurrent decay, namely. the usual power-law dependence cx (-'I2 describing Ihe geminate recombination kinetics in an intinite chain. at times 5 (l0n2W$)-' (W is the diffusion rate, c is the trap concentration), is changed to a &fer exponentiallke dependence 0: r'/6exp(-t'/3). In contrast, it is shown that the photoinduced absorption decay is slowed down due to trapping of photoexcitations by defects. The delayed fluorescence decay caused by recombination of photoexcitations also obeys an exponential-like dependence, cx rr1/2exp(-r1/3), unlike the case ofan infinire chain, when delayed fluorescence decay follows a power-law dependence a fM3l2. The theoretical results are compared with the experimenlal data on relaxation kinetics of photoencitations in nom-polyacetylene and restrictions on the model are considered.

Electrical properties of epitaxial junctions betweenNb:SrTiO3and optimally doped, underdoped, and Zn-dopedRamadan1, Ogale2, Dhar3 et al. 2005Phys. Rev. B353160View full textAdd to dashboardCite

“…Over a decade ago, Hasegawa et al 71 had studied the properties of the contact between the high-T c superconductor Er-Ba-Cu-O and Nb:STO for two cases of Nb doping ͑0.05 wt. % and 0.5 wt.…”

Intrinsic electrical properties of Au/SrTiO3 Schottky junctions

“…Understanding of intrinsic natures of the metal/ STO interface is of great interest in both science and technology of the interface of the transition metal oxides, because the STO is one of the most attractive materials for catalysts, 8 dielectrics, 9 superconductors, 10 and strong electron correlation systems. 11 There are several reports which suggest existence of an interfacial layer in the Schottky junctions between SrTiO 3 :Nb͑STO:Nb͒ and Er-Ba-Cu-O, 12 Y-Ba-Cu-O, 13 BKBO, 14 Au, 13,15 or Pt 16 from dielectric and transport properties of the junctions. However, because of the lack of proper surface treatments to form a well-controlled STO surface and/or rather high substrate temperature in preparing the junctions, precise electrical properties of the metal/STO:Nb Schottky junction have yet been uncertain.…”

Fabrication and characterization of Ba1−xKxBiO3/Nb-doped SrTiO3 all-oxide-type Schottky junctions

“…Both materials have cubic-perovskite crystal structure, and BKBO is a suitable material for basic study on LSBTs because of two primary reasons: ͑i͒ superconducting tunnel junctions using BKBO have a clear superconducting-gap structure and act as an emitter/base junction where quasi particles are injected into a base layer, 2,7-12 ͑ii͒ epitaxial thin films can be grown at low temperatures ͑400-500°C͒. 5,7,8 SrTiO 3 ͑STO͒ is widely used as a substrate for thin film growth of various oxide superconductors, and STNO is an n-type oxide semiconductor which has a high carrier mobility (у10 3 cm 2 /V s) at temperatures below 10 K. 13,14 We have successfully observed the collector current modulation induced by the quasi particle injection from emitter to base layer with a maximum current gain ␣ of about 0.2 for a device structure of Au ͑emitter͒/natural barrier/BKBO ͑base͒/STNO ͑collector͒. 4,6 There are, however, serious problems with using a BKBO/STNO oxide heterojunction as the base/collector junction in an LSBT: poor rectification properties and poor reproducibility.…”

“…All the oxide superconductor/STNO junctions ever reported, on the other hand, exhibited poor Schottky diode properties: a large deviation of n from unity, and large reverse current. 2,13,14 These problems are due to the difficulties of interfacial control for oxide heterojunctions; this control is an important issue not only for the LSBT but also for the crystal engineering using oxide materials.…”