Photo-acoustic response and optical features of 2D-TlGaSe2 and GaAs semiconductors

The paper focuses on investigation of the acoustic-optical properties of 2D-TlGaSe2 and GaAs semiconductors using laser pulses. We present the photo-darkening experiments performed by using CW light in spectral ranges below the band gap of TlGaSe2. The data provides evidence that photo-acoustic signals (PAS) for the above band gap are significantly stronger and linear in 2D-TlGaSe2 while they are distorted by nonlinear processes in isotropic GaAs. The comparison discloses characteristic parameters of TlGaSe2, namely a high factor and a negative sign in the refraction coefficient with pressure, a low absorption coefficient and absence of band filling; all guarantee stabile energy conversion by thermoelastic deformation mechanism. Below the band gap range, we found a new kind of PAS in TlGaSe2 on near surfaces. Likewise, we demonstrate that in such spectral range the giant Stark effect in TlGaSe2 is created by focused CW beams. The Stark effect produces local optical darkening which can provide explosion at extreme light power. Likely, both effects could be related to the planar stacking faults in 2D-TlGaSe2, which produce a spontaneous charge separation on layers.

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LASER-INDUCED MULTIPHOTON PHOTOCONDUCTIVITY IN DIRECT AND INDIRECT BAND GAP CRYSTALS USING Z-SCAN TECHNIQUE

Modern Physics Letters B ◽

10.1142/s0217984909020874 ◽

2009 ◽

Vol 23 (23) ◽

pp. 2783-2789 ◽

Cited By ~ 1

Author(s):

ARUN GAUR ◽

D. K. SHARMA ◽

K. S. SINGH ◽

NAGESHWAR SINGH

Keyword(s):

Absorption Coefficient ◽

Band Gap ◽

Laser Pulses ◽

Beam Waist ◽

Photon Absorption ◽

Nanosecond Laser ◽

Direct Band Gap ◽

Direct Band ◽

Nanosecond Laser Pulses ◽

Indirect Band Gap

Nanosecond laser pulses have employed the photoconductive Z-scan technique. Photoconductivity traces measured by moving the sample across the laser beam waist were used for measuring two and three-photon absorption processes. The value of the three-photon absorption coefficient β3=9.6×10-10 cm 3/ GW 2 in the case of direct, and 8.96×10-12 cm 3/ GW 2 and 5.0×10-12 cm 3/ GW 2 in the case of indirect band gap crystals have been estimated from a comparison of traces measured by exciting the sample with the first and second harmonics of Nd : YAG laser. The low value of β3 in the case of indirect band gap crystals compared to direct band gap crystals is attributed to phonon-assisted transitions.

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Laser Assisted Seeding for Electroless Plating on Insulators

MRS Proceedings ◽

10.1557/proc-285-197 ◽

1992 ◽

Vol 285 ◽

Author(s):

A.G. Schrott ◽

B. Braren ◽

E.J.M. O'sullivan ◽

R.F. Saraf

Keyword(s):

Band Gap ◽

Excimer Laser ◽

Deposition Rate ◽

Electroless Plating ◽

Repetition Rate ◽

Laser Light ◽

Laser Pulses ◽

Electron Excitation ◽

Insulating Materials

ABSTRACTExcimer laser pulses with wavelengths of 248 and 308 nm were used to selectively seed Pd on SiO2 surfaces, making them suitable for electroless plating. This novel seeding process for insulating materials is accomplished with the sample immersed in the seeding solution, and occurs only on the areas of the substrate that are illuminated (through the liquid) by the laser light. The Pd content of the seeded samples increased with the number of pulses, but was rather independent of repetition rate. The deposition rate showed a dependence with wavelength consistent with a defect driven mechanism for electron excitation through the band gap of SiO2. These electrons then reduce the Pd ions in the solution in contact with the surface.

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Characterization of ultrafast free-electron laser pulses using extreme-ultraviolet transient gratings

Journal of Synchrotron Radiation ◽

10.1107/s1600577517015612 ◽

2018 ◽

Vol 25 (1) ◽

pp. 32-38 ◽

Cited By ~ 4

Author(s):

F. Capotondi ◽

L. Foglia ◽

M. Kiskinova ◽

C. Masciovecchio ◽

R. Mincigrucci ◽

...

Keyword(s):

Arrival Time ◽

Extreme Ultraviolet ◽

Laser Pulses ◽

Linear Process ◽

Third Order ◽

X Ray ◽

High Pulse ◽

Spectral Ranges ◽

Pulse Energies

The characterization of the time structure of ultrafast photon pulses in the extreme-ultraviolet (EUV) and soft X-ray spectral ranges is of high relevance for a number of scientific applications and photon diagnostics. Such measurements can be performed following different strategies and often require large setups and rather high pulse energies. Here, high-quality measurements carried out by exploiting the transient grating process,i.e.a third-order non-linear process sensitive to the time-overlap between two crossed EUV pulses, is reported. From such measurements it is possible to obtain information on both the second-order intensity autocorrelation function and on the coherence length of the pulses. It was found that the pulse energy density needed to carry out such measurements on solid state samples can be as low as a few mJ cm−2. Furthermore, the possibility to control the arrival time of the crossed pulses independently might permit the development of a number of coherent spectroscopies in the EUV and soft X-ray regime, such as, for example, photon echo and two-dimensional spectroscopy.

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Second harmonic generation from direct band gap quantum dots pumped by femtosecond laser pulses

Journal of Applied Physics ◽

10.1063/1.4865956 ◽

2014 ◽

Vol 115 (7) ◽

pp. 074303 ◽

Cited By ~ 2

Author(s):

Liwei Liu ◽

Yue Wang ◽

Siyi Hu ◽

Yu Ren ◽

Chen Huang

Keyword(s):

Quantum Dots ◽

Femtosecond Laser ◽

Second Harmonic Generation ◽

Band Gap ◽

Harmonic Generation ◽

Second Harmonic ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Direct Band Gap ◽

Direct Band

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Band-gap renormalization and band filling in Si-doped GaN films studied by photoluminescence spectroscopy

Journal of Applied Physics ◽

10.1063/1.371377 ◽

1999 ◽

Vol 86 (8) ◽

pp. 4400-4402 ◽

Cited By ~ 108

Author(s):

M. Yoshikawa ◽

M. Kunzer ◽

J. Wagner ◽

H. Obloh ◽

P. Schlotter ◽

...

Keyword(s):

Band Gap ◽

Photoluminescence Spectroscopy ◽

Band Filling ◽

Si Doped

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Quasi-two-dimensional electron-hole plasma in GaAs-GaAlAs MQW structures: Band-filling effects and band-gap renormalization

Surface Science ◽

10.1016/0039-6028(86)90410-3 ◽

1986 ◽

Vol 174 (1-3) ◽

pp. 211-215 ◽

Cited By ~ 8

Author(s):

G. Tränkle ◽

H. Leier ◽

A. Forchel ◽

G. Weimann

Keyword(s):

Band Gap ◽

Two Dimensional ◽

Dimensional Electron ◽

Electron Hole ◽

Hole Plasma ◽

Electron Hole Plasma ◽

Band Filling

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SUPERCONTINUUM SPECTRUM GENERATION IN THE LIQUIDS WITH DIFFERENT BAND GAP THRESHOLDS

Journal of Nonlinear Optical Physics & Materials ◽

10.1142/s021886350600344x ◽

2006 ◽

Vol 15 (04) ◽

pp. 447-453

Author(s):

SHIAN ZHANG ◽

ZHENRONG SUN ◽

LI DENG ◽

ZUGENG WANG

Keyword(s):

Band Gap ◽

Laser Energy ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Spectral Broadening ◽

Laser Spectrum ◽

High Laser ◽

Supercontinuum Spectrum ◽

High Laser Energy ◽

Spectrum Generation

Supercontinuum spectrum generation by femtosecond laser pulses propagating in transparent liquids with different band gap thresholds is investigated. As the laser energy increases, the laser spectrum is strongly broadened and modulated, and finally a supercontinuum spectrum can be observed. The spectral broadening can be mainly attributed to the optical Kerr effect at low laser energy and the plasma created by the multiphoton excitation of electrons from the valence band to the conduction band at high laser energy. It is found that the spectral broadening and modulation strongly depend on the band gap threshold E gap of the medium.

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Tunable SnO2 Nanoribbon by Electric Fields and Hydrogen Passivation

Journal of Nanomaterials ◽

10.1155/2017/4815251 ◽

2017 ◽

Vol 2017 ◽

pp. 1-12

Author(s):

Xin-Lian Chen ◽

Bao-Jun Huang ◽

Chang-Wen Zhang ◽

Ping Li ◽

Pei-Ji Wang

Keyword(s):

Band Gap ◽

Electric Fields ◽

Stark Effect ◽

Tin Dioxide ◽

Band Gaps ◽

Hydrogen Passivation ◽

Band Engineering ◽

Metal Semiconductor Metal ◽

Projector Augmented Wave ◽

Electronic Field

Under external transverse electronic fields and hydrogen passivation, the electronic structure and band gap of tin dioxide nanoribbons (SnO2NRs) with both zigzag and armchair shaped edges are studied by using the first-principles projector augmented wave (PAW) potential with the density function theory (DFT) framework. The results showed that the electronic structures of zigzag and armchair edge SnO2NRs exhibit an indirect semiconducting nature and the band gaps demonstrate a remarkable reduction with the increase of external transverse electronic field intensity, which demonstrate a giant Stark effect. The value of the critical electric field for bare Z-SnO2NRs is smaller than A-SnO2NRs. In addition, the different hydrogen passivation nanoribbons (Z-SnO2NRs-2H and A-SnO2NRs-OH) show different band gaps and a slightly weaker Stark effect. The band gap of A-SnO2NRs-OH obviously is enhanced while the Z-SnO2NRs-2H reduce. Interestingly, the Z-SnO2NRs-OH presented the convert of metal-semiconductor-metal under external transverse electronic fields. In the end, the electronic transport properties of the different edges SnO2NRs are studied. These findings provide useful ways in nanomaterial design and band engineering for spintronics.

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