scholarly journals Electric field spectroscopy of material defects in transmon qubits

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Jürgen Lisenfeld ◽  
Alexander Bilmes ◽  
Anthony Megrant ◽  
Rami Barends ◽  
Julian Kelly ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Electric Fields ◽  
Defect Formation ◽  
Tunnel Junctions ◽  
Dipole Moments ◽  
Device Fabrication ◽  
Superconducting Qubits ◽  
Atomic Scale ◽  
Large Area ◽  
Tunnel Barriers

AbstractSuperconducting integrated circuits have demonstrated a tremendous potential to realize integrated quantum computing processors. However, the downside of the solid-state approach is that superconducting qubits suffer strongly from energy dissipation and environmental fluctuations caused by atomic-scale defects in device materials. Further progress towards upscaled quantum processors will require improvements in device fabrication techniques, which need to be guided by novel analysis methods to understand and prevent mechanisms of defect formation. Here, we present a technique to analyse individual defects in superconducting qubits by tuning them with applied electric fields. This provides a spectroscopy method to extract the defects’ energy distribution, electric dipole moments, and coherence times. Moreover, it enables one to distinguish defects residing in Josephson junction tunnel barriers from those at circuit interfaces. We find that defects at circuit interfaces are responsible for about 60% of the dielectric loss in the investigated transmon qubit sample. About 40% of all detected defects are contained in the tunnel barriers of the large-area parasitic Josephson junctions that occur collaterally in shadow evaporation, and only $$\approx$$≈3% are identified as strongly coupled defects, which presumably reside in the small-area qubit tunnel junctions. The demonstrated technique provides a valuable tool to assess the decoherence sources related to circuit interfaces and to tunnel junctions that is readily applicable to standard qubit samples.

scholarly journals Improvement of poly(3-hexylthiophene-2,5-diyl) electron mobility through complete elimination of regioregularity defects

2021 ◽  
Author(s):  
Ali Nawaz ◽  
Marlus Koehler ◽  
Anil Kumar ◽  
Leandro Merces ◽  
Anne B. R. Abreu ◽  
...  
Keyword(s):  
Electron Transport ◽  
Integrated Circuits ◽  
Electron Mobility ◽  
Dipole Moments ◽  
Low Cost ◽  
Large Area ◽  
Polymer Semiconductors ◽  
Current Voltage ◽  
Polymer Metal ◽  
Thiophene Based Polymers

The improvement of electron transport in polymer semiconductors is highly desirable for realizing robust, large-area and low-cost organic integrated circuits. This work investigates the effect of regioregularity on the intrinsic hole and electron transport characteristics of poly(3-hexylthiophene-2,5-diyl) (P3HT) using current-voltage (I-V) measurements in metal/polymer/metal sandwich structures. Through a direct comparison between 93% regioregular P3HT (EG-P3HT) and 100% regioregular defect-free poly(3-hexylthiophene-2,5-diyl) (DF-P3HT), it is found that the elimination of regioregularity defects improves the electron mobility of DF-P3HT (1.05 × 10-7 cm2 V-1 s-1) by three orders of magnitude compared to the 93% regioregular EG-P3HT sample (1.82 × 10-10 cm2 V-1 s-1). Quantum chemical calculations indicate that the improvement of electron mobility in DF-P3HT can be associated to the lower degree of disorder in these samples that tends to increase the transfer angle between the lowest unoccupied molecular orbitals of adjacent chains. At the same time, the lower dipole moments produced by the defect-free polymer molecules also appears to play an important role in decreasing the susceptibility of charge transport to environment-induced electron traps. The obtained results provide a strong evidence that the elimination of regioregularity defects is an effective technique to improve electron transport and restore the symmetry between hole and electron mobility in P3HT as well as other thiophene-based polymers.

Structural changes in silicon-on-insulator material during post-implantation annealing

1986 ◽  
Vol 44 ◽  
pp. 736-737
Author(s):  
C. O. Jung ◽  
S. J. Krause ◽  
S.R. Wilson
Keyword(s):  
Integrated Circuits ◽  
Oxide Layer ◽  
High Speed ◽  
Structural Changes ◽  
Device Fabrication ◽  
Silicon On Insulator ◽  
High Quality ◽  
Radiation Hardened ◽  
Post Implantation ◽  
Very High

Silicon-on-insulator (SOI) structures have excellent potential for future use in radiation hardened and high speed integrated circuits. For device fabrication in SOI material a high quality superficial Si layer above a buried oxide layer is required. Recently, Celler et al. reported that post-implantation annealing of oxygen implanted SOI at very high temperatures would eliminate virtually all defects and precipiates in the superficial Si layer. In this work we are reporting on the effect of three different post implantation annealing cycles on the structure of oxygen implanted SOI samples which were implanted under the same conditions.

Off-axis electron holography applied to the study of interfaces

1992 ◽  
Vol 50 (1) ◽  
pp. 244-245
Author(s):  
J.K. Weiss ◽  
M. Gajdardziska-Josifovska ◽  
M. R. McCartney ◽  
David J. Smith
Keyword(s):  
Electric Fields ◽  
Resolution Enhancement ◽  
Interfacial Structure ◽  
Atomic Scale ◽  
Bulk Property ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Composition And Structure ◽  
Chemical Segregation ◽  
Diffraction Effects

Interfacial structure is a controlling parameter in the behavior of many materials. Electron microscopy methods are widely used for characterizing such features as interface abruptness and chemical segregation at interfaces. The problem for high resolution microscopy is to establish optimum imaging conditions for extracting this information. We have found that off-axis electron holography can provide useful information for the study of interfaces that is not easily obtained by other techniques.Electron holography permits the recovery of both the amplitude and the phase of the image wave. Recent studies have applied the information obtained from electron holograms to characterizing magnetic and electric fields in materials and also to atomic-scale resolution enhancement. The phase of an electron wave passing through a specimen is shifted by an amount which is proportional to the product of the specimen thickness and the projected electrostatic potential (ignoring magnetic fields and diffraction effects). If atomic-scale variations are ignored, the potential in the specimen is described by the mean inner potential, a bulk property sensitive to both composition and structure. For the study of interfaces, the specimen thickness is assumed to be approximately constant across the interface, so that the phase of the image wave will give a picture of mean inner potential across the interface.

Fabrication of Ferromagnetic Tunnel Junctions with ICP Oxidized Tunnel Barriers.

1999 ◽  
Vol 23 (4−2) ◽  
pp. 1281-1284 ◽  
Author(s):  
J. Sugawara ◽  
E. Nakashio ◽  
S. Kumagai ◽  
J. Honda ◽  
Y. Ikeda ◽  
...  
Keyword(s):  
Tunnel Junctions ◽  
Tunnel Barriers

An Overview of 300 mm SOI Starting Wafer Quality and Its Yield Detractors

2005 ◽  
Author(s):  
Pei Y. Tsai ◽  
Junedong Lee ◽  
Paul Ronsheim ◽  
Lindsay Burns ◽  
Richard Murphy ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Device Fabrication ◽  
Sampling Plan ◽  
Silicon On Insulator ◽  
Manufacturing Processes ◽  
Circuit Performance ◽  
Characterization Techniques ◽  
Wafer Manufacturing

Abstract A stringent sampling plan is developed to monitor and improve the quality of 300mm SOI (silicon on insulator) starting wafers procured from the suppliers. The ultimate goal is to obtain the defect free wafers for device fabrication and increase yield and circuit performance of the semiconductor integrated circuits. This paper presents various characterization techniques for QC monitor and examples of the typical defects attributed to wafer manufacturing processes.

scholarly journals Experimental and molecular dynamics studies of an ultra-fast sequential hydrogen plasma process for fabricating phosphorene-based sensors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Rajabali ◽  
H. Asgharyan ◽  
V. Fadaei Naeini ◽  
A. Boudaghi ◽  
B. Zabihi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Dynamics ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Hydrogen Plasma ◽  
Device Fabrication ◽  
Dynamics Simulation ◽  
Red Phosphorus ◽  
Large Area ◽  
Low Concentration

AbstractLow concentration phosphorene-based sensors have been fabricated using a facile and ultra-fast process which is based on an exfoliation-free sequential hydrogen plasma treatment to convert the amorphous phosphorus thin film into mono- or few-layered phosphorene sheets. These sheets have been realized directly on silicon substrates followed by the fabrication of field-effect transistors showing the low leakage current and reasonable mobility for the nano-sensors. Being capable of covering the whole surface of the silicon substrate, red phosphorus (RP) coated substrate has been employed to achieve large area phosphorene sheets. Unlike the available techniques including mechanical exfoliation, there is no need for any exfoliation and/or transfer step which is significant progress in shortening the device fabrication procedure. These phosphorene sheets have been examined using transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Raman spectroscopy and atomic-force microscopy (AFM). Electrical output in different states of the crystallization as well as its correlation with the test parameters have been also extensively used to examine the evolution of the phosphorene sheets. By utilizing the fabricated devices, the sensitivity of the phosphorene based-field effect transistors to the soluble L-Cysteine in low concentrations has been studied by measuring the FET response to the different concentrations. At a gate voltage of − 2.5 V, the range of 0.07 to 0.60 mg/ml of the L-Cysteine has been distinguishably detected presenting a gate-controlled sensor for a low-concentration solution. A reactive molecular dynamics simulation has been also performed to track the details of this plasma-based crystallization. The obtained results showed that the imparted energy from hydrogen plasma resulted in a phase transition from a system containing red phosphorus atoms to the crystal one. Interestingly and according to the simulation results, there is a directional preference of crystal growth as the crystalline domains are being formed and RP atoms are more likely to re-locate in armchair than in zigzag direction.

TRANSPARENCY OF NARROW CONSTRICTIONS IN A GRAPHENE SINGLE ELECTRON TRANSISTOR

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2647-2654 ◽  
Author(s):  
C. STAMPFER ◽  
E. SCHURTENBERGER ◽  
F. MOLITOR ◽  
J. GÜTTINGER ◽  
T. IHN ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Drain Current ◽  
Single Electron ◽  
Single Electron Transistor ◽  
Perpendicular Magnetic Field ◽  
Current Saturation ◽  
Tunnel Barriers ◽  
Graphene Island ◽  
Charging Energy

We report on electronic transport experiments on a graphene single electron transistor as function of a perpendicular magnetic field. The device, which consists of a graphene island connected to source and drain electrodes via two narrow graphene constrictions is electronically characterized and the device exhibits a characteristic charging energy of approx. 3.5 meV. We investigate the homogeneity of the two graphene "tunnel" barriers connecting the single electron transistor to source and drain contacts as function of laterally applied electric fields, which are also used to electrostatically tune the overall device. Further, we focus on the barrier transparency as function of an applied perpendicular magnetic field and we find an increase of transparency for increasing magnetic field and a source-drain current saturation for magnetic fields exceeding 5 T.

scholarly journals Large-area printing of ferroelectric surface and super-domains for efficient solar water splitting

2020 ◽  
Author(s):  
Yu Tian ◽  
Yaqing Wei ◽  
Minghui Pei ◽  
Rongrong Cao ◽  
Zhenao Gu ◽  
...  
Keyword(s):  
Water Splitting ◽  
Electric Fields ◽  
Electronic Structures ◽  
Active Sites ◽  
Large Area ◽  
Solar Water Splitting ◽  
High Efficient ◽  
Catalytic Sites ◽  
Order Of Magnitude ◽  
Magnitude Increase

Abstract Surface electronic structures of the photoelectrodes determine the activity and efficiency of the photoelectrochemical water splitting, but the controls of their surface structures and interfacial chemical reactions remain challenging. Here, we use ferroelectric BiFeO3 as a model system to demonstrate an efficient and controllable water splitting reaction by large-area constructing the hydroxyls-bonded surface. The up-shift of band edge positions at this surface enables and enhances the interfacial holes and electrons transfer through the hydroxyl-active-sites, leading to simultaneously enhanced oxygen and hydrogen evolutions. Furthermore, printing of ferroelectric super-domains with microscale checkboard up/down electric fields separates the distribution of reduction/oxidation catalytic sites, enhancing the charge separation and giving rise to an order of magnitude increase of the photocurrent. This large-area printable ferroelectric surface and super-domains offer an alternative platform for controllable and high-efficient photocatalysis.

scholarly journals Microwave Assisted Synthesis of Organic Compounds and Nanomaterials

2021 ◽  
Author(s):  
Anjali Jha
Keyword(s):  
Green Chemistry ◽  
Organic Synthesis ◽  
Electric Fields ◽  
Chemical Reactions ◽  
Dipole Moments ◽  
Electric Heating ◽  
Microwave Assisted Synthesis ◽  
Microwave Chemistry ◽  
Microwave Assisted ◽  
Promising Area

In the Conventional laboratory or industry heating technique involve Bunsen burner, heating mental/hot plates and electric heating ovens. To produce a variety of useful compounds for betterment of mankind, the Microwave Chemistry was introduced in year 1955 and finds a place in one of the Green chemistry method. In Microwave chemistry is the science of applying microwave radiation to chemical reactions. Microwaves act as high frequency electric fields and will generally heat any material containing mobile electric charges, such as polar molecules in a solvent or conducting ions in a solid. Polar solvents are heated as their component molecules are forced to rotate with the field and lose energy in collisions i.e. the dipole moments of molecules are important in order to proceed with the chemical reactions in this method. It can be termed as microwave-assisted organic synthesis (MAOS), Microwave-Enhanced Chemistry (MEC) or Microwave-organic Reaction Enhancement synthesis (MORE). Microwave-Assisted Syntheses is a promising area of modern Green Chemistry could be adopted to save the earth.

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