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Deep Traps (deep + trap)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Specific features of 3.8-eV emission in TL spectra of oxygen-deficient corundum

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2005
I. A. Weinstein
Abstract The behavior of the 3.8-eV band in the thermoluminescence spectrum of anion-deficient single crystals of ,-Al2O3 has been analyzed as a function of the state of the deep trap at 730 K. A linear correlation between the TL response of the main dosimetric peak at this band and the occupancy of the said deep trap has been established using the method of stepwise emptying. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Potentiometry on pentacene OFETs: Charge carrier mobilities and injection barriers in bottom and top contact configurations

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2008
R. Scholz
Abstract In a combination of experimental techniques including electrical probes, potentiometry, and charge transient spectroscopy (QTS), we develop concepts how to quantify the potential drops at the contacts, the mobility in the channel region, and the density of states of deep traps in pentacene OFETs. For OFETs grown from unpurified pentacene on pre-patterned Au bottom contacts, a comparison between potentiometry and two-dimensional device simulations determines an injection barrier of 0.73 eV at the source contact and a hole mobility of 0.014 cm2 V,1 s,1 in the pentacene channel. Temperature-dependent QTS data reveal a trap level at about 125 meV from the hole transport band, indicating a relatively high density of unintentional dopants and therefore a high background density of majority charge carriers. In OFETs grown from purified pentacene onto a SiO2 gate dielectric and Au top contacts evaporated onto the pentacene channel without breaking the vacuum, potentiometry reveals a nearly perfect alignment of the metal work function with the hole transport level in the organic layer. The much lower density of deep traps in these samples raises the hole mobility to the range 0.1,0.2 cm2 V,1 s,1. A further improvement of the hole mobility and the resulting device performance can be achieved by a chemical treatment of the gate oxide with n-octadecytrichlorosilane (OTS). (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Hydrogenation and oxygenation of the (100) diamond surface and the consequences for transfer doping

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2005
S. J. Sque
Abstract Ab initio density-functional-theory calculations have been performed to determine the structural and electronic properties of the (100) diamond surface with various hydrogen and oxygen terminations. Total energies indicate that an ,OH-terminated surface is favoured over an oxygenated surface plus gas-phase hydrogen. Ionisation potentials and electron affinities (EAs) are reported for the different systems, and the distinction is made between bulk- and surface-related properties. A first-order correction is used to offer estimated surface EAs. A negative bulk EA is found for surfaces terminated with ,H and ,OH groups, although many surfaces have deep traps which can act as positive EA in the absence of band bending. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Analysis of traps in CVD diamond films through thermal depumping of nuclear detectors

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2004
A. Balducci
Abstract Carrier free paths in Chemical Vapour Deposition (CVD) diamond films depend on the presence of traps, which therefore strongly affect the performance of those CVD diamond based devices which rely on the electronic properties of the material, like radiation detectors. For the same reason, these devices can in turn be used as tools to study carrier dynamics. It is well known that some traps may be saturated by pre-irradiation with ionizing radiation (e.g. ,-particles), a process called "pumping" or "priming". Not all traps behave in the same way. Due to the large bandgap of diamond, both shallow (not affected by pumping) and deep traps for electrons and holes may exist. We measured, using 5.5 MeV 241Am ,-particles, the response of high quality CVD diamond based detectors after successive annealing steps performed at selected temperatures. The analisys of the decay of the detector efficency with annealing time at several temperatures allows a quantitative evaluation of the activation energy of these defects. Two main trapping centres connected to the pumping process were found, both related to holes, having activation energies of about 1.6 eV and 1.3 eV respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Comparison of deep level incorporation in ammonia and rf-plasma assisted molecular beam epitaxy n-GaN films

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008
A. R. Arehart
Abstract The use of rf-plasma and ammonia nitrogen sources for growth of GaN films by molecular beam epitaxy (MBE) are compared in terms of defect incorporation using deep level optical spectroscopy (DLOS) and deep level transient spectroscopy (DLTS). To better improve the understanding of ammonia-based MBE growth of GaN and potential defect sources as opposed to the more studied plasma source-based MBE-grown material several V/III ratios were also investigated, which were generated via systematic adjustment of the ammonia flow rates during growth. The DLOS spectra, comparing deep traps within the n-GaN grown using N-plasma and ammonia sources, reveal the presence of the same deep levels due to background carbon and gallium vacancies, with energy levels at EC -3.28, EC -2.62, and EC -1.28. The DLTS results of the N-plasma and ammonia-based MBE samples show two similarly dominant electron traps at EC -0.60, and EC -0.24 in each sample. Measurements made as a function of V/III flux ratio for ammonia-based MBE growth indicate a large dependence of the EC -0.24 eV trap concentration on growth flux ratio, which is significant for guiding continued optimization of this promising MBE growth method for GaN devices. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]