Optical Direct and Indirect Excitation of Er3+ Ions in Silicon

AbstractOptical direct and indirect excitation of erbium (Er) ions in silicon substrates was performed in order to investigate the high efficiency of Er3+− related 1.54μm emission (4I13/2→4I15/2) for direct excitation that is not concerned with the indirect band gap and low quantum efficiency of a Si host. The samples were prepared by ion-implantation or thermal diffusion methods. In each sample, photoluminescence (PL) showed the peaks originating from 4I13/2→4I15/2 of Er3+ ions.In Er thermally diffused samples, optical excitation for energy level 4I11/2 of Er3+ ions was successfully effected by photoluminescence excitation spectroscopy (PLE). The PLE spectra consisted six peaks (963.1nm, 965.0nm, 976.lnm, 978.9nm and 980.9nm) which were caused by direct excitation (4I15/2→4I11/2) of Er3+ ions. The emission directly excited is about 2 times more intense than the indirectly excited emission. The six peaks originating from the splitting of the 4I11/2 levels meant that Er3+ ions were in the sites of noncubic symmetry. The samples prepared by Er ion-implantation did not show the effect.

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Optical Direct and Indirect Excitation of Er3+ Ions In Silicon

MRS Proceedings ◽

10.1557/proc-301-107 ◽

1993 ◽

Vol 301 ◽

Cited By ~ 5

Author(s):

A. Majima ◽

S. Uekusa ◽

K. Ootake ◽

K. Abe ◽

M. Kumagai

Keyword(s):

Energy Level ◽

Ion Implantation ◽

Band Gap ◽

Thermal Diffusion ◽

High Efficiency ◽

Optical Excitation ◽

Silicon Substrates ◽

Photoluminescence Excitation ◽

Direct Excitation ◽

Indirect Band Gap

ABSTRACTOptical direct and indirect excitation of erbium (Er) ions in silicon substrates was performed in order to investigate the high efficiency of Er3+− related 1.54µm emission (4I13/2→4I15/2) for direct excitation that is not concerned with the indirect band gap and low quantum efficiency of a Si host. The samples were prepared by ion-implantation or thermal diffusion methods. In each sample, photoluminescence (PL) showed the peaks originating from 4I13/2→4I15/2 of Er3+ ions.In Er thermally diffused samples, optical excitation for energy level 4I11/2 of Er3+ ions was successfully effected by photoluminescence excitation spectroscopy (PLE). The PLE spectra consisted six peaks (963. lnm, 965.Onm, 976.lnm, 978.9nm and 980.9nm) which were caused by direct excitation (4I15/2→4I11/2) of Er3+ ions. The emission directly excited is about 2 times more intense than the indirectly excited emission. The six peaks originating from the splitting of the 4I11/2 levels meant that Er3+ ions were in the sites of noncubic symmetry. The samples prepared by Er ion-implantation did not show the effect.

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Indirect band gap of coherently strainedGexSi1−xbulk alloys on〈001〉silicon substrates

Physical Review B ◽

10.1103/physrevb.32.1405 ◽

1985 ◽

Vol 32 (2) ◽

pp. 1405-1408 ◽

Cited By ~ 380

Author(s):

R. People

Keyword(s):

Band Gap ◽

Silicon Substrates ◽

Indirect Band Gap

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Two-dimensional like conjugated copolymers for high efficiency bulk-heterojunction solar cell application: Band gap and energy level engineering

Science China Chemistry ◽

10.1007/s11426-011-4257-3 ◽

2011 ◽

Vol 54 (4) ◽

pp. 685-694 ◽

Cited By ~ 30

Author(s):

ChunHui Duan ◽

ChuanDao Wang ◽

ShengJian Liu ◽

Fei Huang ◽

C. H. Wallace Choy ◽

...

Keyword(s):

Solar Cell ◽

Energy Level ◽

Band Gap ◽

High Efficiency ◽

Bulk Heterojunction ◽

Heterojunction Solar Cell ◽

Two Dimensional ◽

Solar Cell Application ◽

Bulk Heterojunction Solar Cell ◽

Conjugated Copolymers

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Artificial Atoms of Silicon

MRS Proceedings ◽

10.1557/proc-582-h2.5 ◽

1999 ◽

Vol 582 ◽

Author(s):

Justin D. Holmes ◽

Kirk J. Ziegler ◽

Keith P. Johnston ◽

R. Chris Doty ◽

Brian A. Korgel

Keyword(s):

Quantum Yield ◽

Band Gap ◽

Silicon Nanocrystals ◽

Room Temperature ◽

Band Edge ◽

Electronic Transitions ◽

Photoluminescence Excitation ◽

Blue Band ◽

Artificial Atoms ◽

Indirect Band Gap

ABSTRACTSize-monodisperse, stable 15 Å diameter silicon nanocrystals were synthesized in significant quantities using supercritical octanol as a capping ligand. The silicon nanocrystals exhibit an indirect band gap with discrete electronic transitions in the absorbance and photoluminescence excitation (PLE) spectra. The octanol-capped clusters show efficient blue band-edge photoemission with a luminescence quantum yield of 23 % at room temperature.

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Structural fluctuations cause spin-split states in tetragonal (CH3NH3)PbI3 as evidenced by the circular photogalvanic effect

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1805422115 ◽

2018 ◽

Vol 115 (38) ◽

pp. 9509-9514 ◽

Cited By ~ 45

Author(s):

Daniel Niesner ◽

Martin Hauck ◽

Shreetu Shrestha ◽

Ievgen Levchuk ◽

Gebhard J. Matt ◽

...

Keyword(s):

Band Gap ◽

Tetragonal Phase ◽

High Efficiency ◽

Polarized Light ◽

Spin Splitting ◽

Rashba Effect ◽

Photogalvanic Effect ◽

Circularly Polarized Light ◽

Structural Fluctuations ◽

Indirect Band Gap

Lead halide perovskites are used in thin-film solar cells, which owe their high efficiency to the long lifetimes of photocarriers. Various calculations find that a dynamical Rashba effect could significantly contribute to these long lifetimes. This effect is predicted to cause a spin splitting of the electronic bands of inversion-symmetric crystalline materials at finite temperatures, resulting in a slightly indirect band gap. Direct experimental evidence of the existence or the strength of the spin splitting is lacking. Here, we resonantly excite photocurrents in single crystalline (CH3NH3)PbI3 with circularly polarized light to clarify the existence of spin splittings in the band structure. We observe a circular photogalvanic effect, i.e., the photocurrent depends on the light helicity, in both orthorhombic and tetragonal (CH3NH3)PbI3. At room temperature, the effect peaks for excitation photon energies ΔE=110 meV below the direct optical band gap. Temperature-dependent measurements reveal a sign change of the effect at the orthorhombic–tetragonal phase transition, indicating different microscopic origins in the two phases. Within the tetragonal phase, both ΔE and the amplitude of the circular photogalvanic effect increase with temperature. Our findings support a dynamical Rashba effect in this phase, i.e., a spin splitting caused by thermally induced structural fluctuations which break inversion symmetry.

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Erratum: Indirect band gap of coherently strainedGexSi1−xbulk alloys on silicon substrates

Physical Review B ◽

10.1103/physrevb.33.1451.2 ◽

1986 ◽

Vol 33 (2) ◽

pp. 1451-1451

Author(s):

R. People

Keyword(s):

Band Gap ◽

Silicon Substrates ◽

Indirect Band Gap

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Transparent All-Oxide Hybrid NiO:N/TiO2 Heterostructure for Optoelectronic Applications

Electronics ◽

10.3390/electronics10090988 ◽

2021 ◽

Vol 10 (9) ◽

pp. 988

Author(s):

Chrysa Aivalioti ◽

Alexandros Papadakis ◽

Emmanouil Manidakis ◽

Maria Kayambaki ◽

Maria Androulidaki ◽

...

Keyword(s):

Band Gap ◽

Single Phase ◽

Structural Disorder ◽

Energy Band Gap ◽

Nitrogen Doped ◽

Nio Thin Film ◽

Direct Band ◽

Output Characteristics ◽

Indirect Band Gap ◽

P Type

Nickel oxide (NiO) is a p-type oxide and nitrogen is one of the dopants used for modifying its properties. Until now, nitrogen-doped NiO has shown inferior optical and electrical properties than those of pure NiO. In this work, we present nitrogen-doped NiO (NiO:N) thin films with enhanced properties compared to those of the undoped NiO thin film. The NiO:N films were grown at room temperature by sputtering using a plasma containing 50% Ar and 50% (O2 + N2) gases. The undoped NiO film was oxygen-rich, single-phase cubic NiO, having a transmittance of less than 20%. Upon doping with nitrogen, the films became more transparent (around 65%), had a wide direct band gap (up to 3.67 eV) and showed clear evidence of indirect band gap, 2.50–2.72 eV, depending on %(O2-N2) in plasma. The changes in the properties of the films such as structural disorder, energy band gap, Urbach states and resistivity were correlated with the incorporation of nitrogen in their structure. The optimum NiO:N film was used to form a diode with spin-coated, mesoporous on top of a compact, TiO2 film. The hybrid NiO:N/TiO2 heterojunction was transparent showing good output characteristics, as deduced using both I-V and Cheung’s methods, which were further improved upon thermal treatment. Transparent NiO:N films can be realized for all-oxide flexible optoelectronic devices.

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Enhanced luminescence/photodetecting bifunctional devices based on ZnO:Ga microwire/p-Si heterojunction by incorporating Ag nanowires

Nanoscale Advances ◽

10.1039/d1na00428j ◽

2021 ◽

Author(s):

Mingming Jiang ◽

Yang Liu ◽

Ruiming Dai ◽

Kai Tang ◽

Peng Wan ◽

...

Keyword(s):

Band Gap ◽

Carrier Mobility ◽

Lattice Mismatch ◽

Semiconductor Materials ◽

Large Lattice ◽

Ag Nanowires ◽

Large Lattice Mismatch ◽

Enhanced Luminescence ◽

Indirect Band Gap

Suffering from the indirect band gap, low carrier mobility, and large lattice mismatch with other semiconductor materials, one of the current challenges in Si-based materials and structures is to prepare...

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