Transition Metal Excited States in Silicon

1987 ◽  
Vol 104 ◽  
Author(s):  
M. Kleverman ◽  
J. Olajos ◽  
G. Grossmann ◽  
H. G. Grimmeiss
Keyword(s):  
Transition Metal ◽  
Excited States ◽  
Point Group ◽  
Uniaxial Stress ◽  
Shallow Donor ◽  
Group Symmetry ◽  
State Transitions ◽  
Resonance Effects ◽  
Metal Impurities ◽  
Donor States

ABSTRACTRecent absorption and photoconductivity studies of deep transition-metal impurities in silicon are discussed, with emphasis on optical transitions from the deep ground state to shallow Coulomb excited states. The P3/2 line spectra of the deep Au and Pt acceptors closely resemble those of group II acceptors in silicon, whereas the P1/2 lines show resonance effects due to interaction with the valence band continuum. Behavior under uniaxial stress is compatible with D2d or C 2y point-group symmetry for the Au and Pt acceptors. A line spectrum in g-dopes Si can be attributed to excitations to shallow donor states since the phononassisted Fano resonances involve characteristic inter-valley phonons. Both the Ag donor spectrum and the corresponding Au spectrum are dominated by excited s-state transitions. Thus, the traditional fingerprint of a donor in silicon, i.e. the effective-mass like p-state series, is missing or at best observed weakly

scholarly journals Влияние одноосной деформации в направлении [110] на релаксацию состояний мелких доноров мышьяка в германии

2020 ◽  
Vol 54 (9) ◽  
pp. 918
Author(s):  
В.В. Цыпленков ◽  
В.Н. Шастин
Keyword(s):  
Energy Levels ◽  
Optical Excitation ◽  
Uniaxial Stress ◽  
Shallow Donor ◽  
Stimulated Emission ◽  
Relaxation Rates ◽  
Emission Frequency ◽  
Donor States ◽  
Uniaxial Compressive Stress ◽  
Intracenter Transitions

Analysis of acoustical phonon assisted relaxation rates of arsenic donor states has been carried out in depends on uniaxial compressive stress of crystal along [110] direction under low temperature (< 10 K). As shown, under optical excitation the inversion population of donor energy levels is formed that depends on deformation of crystal. This give grounds to suppose that stimulated emission on arsenic shallow donor intracenter transitions in THz range is possible under optical excitation. As shown, uniaxial stress along [110] direction can result to switch laser transition and stimulated emission frequency

scholarly journals Aqueous Corrosion of Aluminum-Transition Metal Alloys Composed of Structurally Complex Phases: A Review

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5418
Author(s):  
Libor Ďuriška ◽  
Ivona Černičková ◽  
Pavol Priputen ◽  
Marián Palcut
Keyword(s):  
Chemical Composition ◽  
Transition Metal ◽  
Noble Metals ◽  
Point Group ◽  
Electrochemical Activity ◽  
Physical Contact ◽  
Localized Corrosion ◽  
Group Symmetry ◽  
Aqueous Corrosion ◽  
Corrosion Properties

Complex metallic alloys (CMAs) are materials composed of structurally complex intermetallic phases (SCIPs). The SCIPs consist of large unit cells containing hundreds or even thousands of atoms. Well-defined atomic clusters are found in their structure, typically of icosahedral point group symmetry. In SCIPs, a long-range order is observed. Aluminum-based CMAs contain approximately 70 at.% Al. In this paper, the corrosion behavior of bulk Al-based CMAs is reviewed. The Al–TM alloys (TM = transition metal) have been sorted according to their chemical composition. The alloys tend to passivate because of high Al concentration. The Al–Cr alloys, for example, can form protective passive layers of considerable thickness in different electrolytes. In halide-containing solutions, however, the alloys are prone to pitting corrosion. The electrochemical activity of aluminum-transition metal SCIPs is primarily determined by electrode potential of the alloying element(s). Galvanic microcells form between different SCIPs which may further accelerate the localized corrosion attack. The electrochemical nobility of individual SCIPs increases with increasing concentration of noble elements. The SCIPs with electrochemically active elements tend to dissolve in contact with nobler particles. The SCIPs with noble metals are prone to selective de-alloying (de–aluminification) and their electrochemical activity may change over time as a result of de-alloying. The metal composition of the SCIPs has a primary influence on their corrosion properties. The structural complexity is secondary and becomes important when phases with similar chemical composition, but different crystal structure, come into close physical contact.

Identification of the Double Acceptor States of Some Transition Metal Impurities in GaAs

1985 ◽  
Vol 46 ◽  
Author(s):  
A.M. Hennel
Keyword(s):  
Magnetic Field ◽  
High Pressure ◽  
Transition Metal ◽  
Energy Gap ◽  
Uniaxial Stress ◽  
Acceptor State ◽  
Metal Impurities ◽  
Transition Metal Impurities ◽  
Optical Line ◽  
Cobalt And Nickel

AbstractThe double acceptor states of chromium, cobalt and nickel were identified by means of the optical and transport measurements under external fields such as hydrostatic pressure, uniaxial stress and magnetic field. The axial fields enable us to observe optical line splittings, which give information about defect symmetries. This technique has been used to identify a double acceptor state of nickel in the GaAs energy gap. High pressure eliminates a degeneracy between defect levels and crystal bands. This leads to activation of new charge states of some impurities. In the case of chromium and cobalt impurities, their double acceptor levels were found to be degenerate with the conduction band of GaAs. A trend existing for the energies of the double acceptor levels permits us to conclude that there will be no other acceptors among the transition metal impurities in GaAs.

scholarly journals Study on structures and electronic properties of NaxV (x=1-12) atomic clusters

2014 ◽  
Vol 17 (4) ◽  
pp. 83-91
Author(s):  
Thanh Tho Bui ◽  
Khung Moc Trang ◽  
Hong Van Nguyen
Keyword(s):  
Transition Metal ◽  
Point Group ◽  
Atomic Clusters ◽  
Group Symmetry ◽  
Chemical Hardness ◽  
Fragmentation Energy ◽  
Metal Atoms ◽  
Transition Metal Atoms ◽  
Theoretical Results ◽  
Negative Total Energy

Superatoms, novel entities being studied extensively in recent years, can be stabilized by mixing with transition metal atoms. The aim of this paper is to present some recent theoretical results on the application of quantum calculations for examining the atomic clusters NaxV (x=1-12) made from the mixing of Nax superatoms with vanadium transition metal atom. Optimized structures of NaxV, NaxV+ and NaxV- are determined by using the TPSSTPSS / DZVP DFT calculations. Characteristics of optimized structures, as point group symmetry, chemical hardness (η), absolute electronegativity (χ), electrophilicity index (ω), fragmentation energy (Ef), secondary energy (∆2E), are calculated. The obtained results point out that among different structures of an atomic cluster, the more negative total energy the more stable structure and the Na8V cluster is the most stable in NaxV (x=1-12) clusters.

Effect of uniaxial stress on intervalley phonon-assisted relaxation of excited shallow-donor states in silicon

2009 ◽  
Vol 43 (11) ◽  
pp. 1410-1415 ◽  
Author(s):  
V. V. Tsyplenkov ◽  
K. A. Kovalevsky ◽  
V. N. Shastin
Keyword(s):  
Uniaxial Stress ◽  
Shallow Donor ◽  
Donor States

scholarly journals Внутрицентровая релаксация мелких доноров сурьмы в деформированном германии

2019 ◽  
Vol 53 (10) ◽  
pp. 1372
Author(s):  
В.В. Цыпленков ◽  
В.Н. Шастин
Keyword(s):  
Excited States ◽  
Measurement Data ◽  
Uniaxial Stress ◽  
Crystallographic Direction ◽  
Probe Method ◽  
Relaxation Rates ◽  
Germanium Crystal ◽  
Pump Probe ◽  
Long Wave ◽  
Donor States

Long-wave acoustic phonons assisted relaxation ratesof the lower excited states 1s(T), 2p0, 2s, 3p0, 2p±, 4p0,3p±of antimony donors in a germanium crystal are calculated.The influence of uniaxial stress in the crystallographic direction[111]on relaxation rates has been considered. The calculationresults have been compared with the measurement data ofrelaxation times of nonequilibrium donor states by the pump-probe method. A comparison is also made with the lifetimesobtained experimentally by the method of studying submillimeterphotoconductivity.

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