jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 Feb 2012

Volume 111, Issue 4, Articles (04xxxx)

Issue Cover Spotlight Figure

J. Appl. Phys. 111, 043501 (2012); http://dx.doi.org/10.1063/1.3680881 (8 pages)

Gregory J. McGraw and Stephen R. Forrest
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds
back to top Lasers, Optics, and Optoelectronics

Photothermal and thermo-refractive effects in high reflectivity mirrors at room and cryogenic temperature

Alessandro Farsi, Mario Siciliani de Cumis, Francesco Marino, and Francesco Marin

J. Appl. Phys. 111, 043101 (2012); http://dx.doi.org/10.1063/1.3684626 (12 pages) | Cited 1 time

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Increasing requirements in the sensitivity of interferometric measurements is a common feature of several research fields, from gravitational wave detection to quantum optics. This motivates refined studies of high reflectivity mirrors and of noise sources that are tightly related to their structure. In this work we present an experimental characterization of photothermal and thermo-refractive effects in high reflectivity mirrors, i.e., of the variations in the position of their effective reflection plane due to weak residual power absorption. The measurements are performed by modulating the impinging power in the range 10Hz÷100kHz. The experimental results are compared with an expressly derived theoretical model in order to fully understand the phenomena and exploit them to extract useful effective thermo-mechanical parameters of the coating. The measurements are extended to cryogenic temperature, where most high sensitivity experiments are performed (or planned in future versions) and where characterizations of dielectric film coatings are still poor.
Show PACS
42.79.Bh Lenses, prisms and mirrors
07.60.Ly Interferometers
42.79.Wc Optical coatings

Microstructured silicon with two impurity bands for solar cells

Huili He, Changshui Chen, and Songhao Liu

J. Appl. Phys. 111, 043102 (2012); http://dx.doi.org/10.1063/1.3684669 (7 pages)

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A low-cost, large area, random, maskless texturing scheme independent of crystal orientation is expected to have an impact on terrestrial photovoltaic technology significantly. We investigated microstructured silicon formed by irradiating the surface of a Si wafer with femtosecond laser pulses in the presence of a sulfur-bearing gas. It is widely believed that microstructured silicon is a potential material for efficient multi intermediate bands silicon solar cell. Using a four-band model, the loss of sunlight for silicon with two different chalcogenide impurity bands was analyzed, and the levels of the minimum loss of sunlight can be found. Then the effect of the position at which the intermediate bands that have minimum sunlight loss rate on the theoretical conversion efficiency of the corresponding solar cell was discussed with the Detailed Balance Theory. After that, the influence of impact ionization on the efficiency of four-band Solar Cells was analyzed in detail. Finally, problems that need to be resolved in making intermediate band solar cell based on femtosecond laser microstructured silicon are pointed out with great emphasis.
Show PACS
88.40.H- Solar cells (photovoltaics)

Formation of carriers in Ti-oxide thin films by substitution reactions

Y. S. Liu, Y. H. Lin, Y. S. Wei, and C. Y. Liu

J. Appl. Phys. 111, 043103 (2012); http://dx.doi.org/10.1063/1.3685448 (6 pages)

Online Publication Date: 16 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Conductive Ti-oxide thin films are produced using a reactive sputtering and post-annealing process. The lowest resistivity of Ti-oxide thin films (2.30 × 10–2 Ω-cm) can be achieved after annealing for 1 h at 400 °C in ambient O2. Additionally, the Hall measurement results indicate that the carrier concentration increases during the initial 1-h annealing process before decreasing during subsequent annealing. By curve fitting the Ols core-level peaks in the x ray photoelectron spectroscopy (XPS) spectrum of the annealed Ti-oxide thin films, we found that the oxygen (O) vacancy concentration monotonically increases with annealing time, which differs from the behavior of the carrier concentration regarding annealing time. This means that the O-vacancy mechanism alone cannot explain the formation of carriers in Ti-oxide thin films. By curve-fitting core-level Ti peaks in the XPS spectrum of annealed Ti-oxide thin films, a Ti3+-to-Ti4+ substitution reaction in the TiO2 phase of the Ti-oxide thin film after annealing plays the dominant role in the formation of conduction carriers. Instead of the O-vacancy mechanism, the Ti3+-to-Ti4+ substitution mechanism can explain the concentration of carriers in Ti-oxide thin films following annealing.
Show PACS
73.61.Le Other inorganic semiconductors
68.55.ag Semiconductors
82.30.Hk Chemical exchanges (substitution, atom transfer, abstraction, disproportionation, and group exchange)
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
81.15.Cd Deposition by sputtering
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Energy transfer in CaYAlO4: Ce3+, Pr3+ for sensitization of quantum-cutting with the Pr3+-Yb3+ couple

A. Guille, A. Pereira, G. Breton, A. Bensalah-Ledoux, and B. Moine

J. Appl. Phys. 111, 043104 (2012); http://dx.doi.org/10.1063/1.3686614 (5 pages) | Cited 3 times

Online Publication Date: 17 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Silicon based solar cells show a poor yield in the UV-blue range of the solar spectrum. The thermalization of the charge carriers is one major loss mechanism, which could be overcome by depositing a quantum-cutting material in front of the solar cell. This phenomenon has recently been demonstrated in materials doped with the rare-earth couple Pr3+-Yb3+, where Pr3+ is able to sensitize two Yb3+ ion for one absorbed blue photon. Unfortunately, the weak absorption cross-section of Pr3+ ion makes it not suitable for thin films applications. Therefore, it is necessary to sensitize it to obtain a significant light yield. In that respect, Ce3+ ion could be used as a sensitizer of Pr3+ because its 4f-5d transition shows a high cross-section absorption. The purpose of this article is to study energy transfers between Ce3+ and Pr3+ in CaYAlO4 with a view to evaluate the potential of Ce3+ as a sensitizer of quantum-cutting with Pr3+-Yb3+ couple. We present results obtained in the bulk material and in a thin film deposited by pulsed laser deposition and we demonstrate that, in CaYAlO4, Ce3+ ion sensitizes the 3Pj levels of Pr3+ ion, but also that this may be followed by a cross-relaxation involving the 4f levels of Ce3+ ion, which would be in competition with energy transfer toward Yb3+ ion.
Show PACS
88.40.H- Solar cells (photovoltaics)
88.40.J- Types of solar cells
68.55.-a Thin film structure and morphology
81.15.Fg Pulsed laser ablation deposition
78.40.Fy Semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Electronic and optical properties of quantum wells embedded in wrinkled nanomembranes

P. Cendula, S. Kiravittaya, and O. G. Schmidt

J. Appl. Phys. 111, 043105 (2012); http://dx.doi.org/10.1063/1.3684544 (5 pages) | Cited 1 time

Online Publication Date: 21 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors theoretically investigate quantum confinement and transition energies in quantum wells (QWs) asymmetrically positioned in wrinkled nanomembranes. Calculations reveal that the wrinkle profile induces both blue- and redshifts, depending on the lateral position of the QW probed. Relevant radiative transitions include the ground state of the electron (hole) and excited states of the hole (electron). Energy shifts as well as stretchability of the structure are studied as a function of wrinkle amplitude and period. Large tunable bandwidths of up to 70 nm are predicted for highly asymmetric, wrinkled QWs.
Show PACS
78.67.De Quantum wells
73.63.Hs Quantum wells
81.07.St Quantum wells
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Crystallization and surface texturing of amorphous-Si induced by UV laser for photovoltaic application

Lei Hong, Xincai Wang, Rusli, Hao Wang, Hongyu Zheng, and Hongyu Yu

J. Appl. Phys. 111, 043106 (2012); http://dx.doi.org/10.1063/1.3686612 (6 pages) | Cited 2 times

Online Publication Date: 22 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The DPSS Nd:YVO4 UV laser is used to anneal amorphous silicon (a-Si) film to achieve crystallization and nano-dome surface texturing simultaneously in a one-step annealing process. With pulse energy of 380 mJ/cm2 and repetition rate of 20 kHz, the a-Si can be crystallized by the sequential lateral solidification process, which is evidenced by both SEM characterization and Raman spectra. In addition, the nano-dome like structure is confirmed by AFM characterization, which can lead to ∼200% boost in terms of light absorption as measured by UV-Visible - Near-infrared scanning spectrophotometer. This study highlights the great potential of Nd:YVO4 UV laser for its application in thin film Si solar cell industry to improve the film quality and light trapping capability.
Show PACS
81.05.Cy Elemental semiconductors
68.55.jm Texture
81.30.Fb Solidification
81.05.Gc Amorphous semiconductors
78.66.Jg Amorphous semiconductors; glasses
78.66.Db Elemental semiconductors and insulators

High density InAlAs/GaAlAs quantum dots for non-linear optics in microcavities

R. Kuszelewicz, J.-M. Benoit, S. Barbay, A. Lemaître, G. Patriarche, K. Meunier, A. Tierno, and T. Ackemann

J. Appl. Phys. 111, 043107 (2012); http://dx.doi.org/10.1063/1.3682466 (9 pages) | Cited 1 time

Online Publication Date: 22 February 2012

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
Structural and optical properties of InAlAs/GaAlAs quantum dots grown by molecular beam epitaxy are studied using transmission electron microscopy and temperature- and time-resolved photoluminescence. The control of the recombination lifetime (50 ps-1.25 ns) and of the dot density (5.10–8-2.1011 cm–3) strongly suggest that these material systems can find wide applications in opto-electronic devices as focusing non-linear dispersive materials as well as fast saturable absorbers.
Show PACS
68.65.Hb Quantum dots (patterned in quantum wells)
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
78.67.Hc Quantum dots
81.07.Ta Quantum dots
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Ground-state power quenching in two-state lasing quantum dot lasers

Mariangela Gioannini

J. Appl. Phys. 111, 043108 (2012); http://dx.doi.org/10.1063/1.3682574 (9 pages) | Cited 1 time

Online Publication Date: 22 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The paper analyses theoretically the quenching of the ground state (GS) power observed in InAs/GaAs quantum dot lasers when emitting simultaneously from both ground state and excited state. The model, based on a set of rate equations for the electrons, holes, and photons, shows that the power quenching is caused by the different time scales of the electron and hole intra-level dynamic, as well as by the long transport time of the holes in the GaAs barrier. The results presented also evidence how the very different dynamics of electrons and holes have other important consequences on the laser behavior; we show for example that the electron and hole carrier densities of the states resonant with lasing modes are never clamped at the threshold value, and that the damping of relaxation oscillations is strongly influenced by the hole dynamics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes

Detecting and tuning anisotropic mode splitting induced by birefringence in an InGaAs/GaAs/AlGaAs vertical-cavity surface-emitting laser

J. L. Yu, Y. H. Chen, C. Y. Jiang, X. L. Ye, and H. Y. Zhang

J. Appl. Phys. 111, 043109 (2012); http://dx.doi.org/10.1063/1.3682648 (4 pages) | Cited 1 time

Online Publication Date: 22 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The mode splitting induced by birefringence in an InGaAs/GaAs/AlGaAs vertical-cavity surface-emitting laser (VCSEL) has been studied by reflectance difference spectroscopy (RDS) at room temperature. The mode splitting, anisotropic broadening width, and the anisotropic integrated area of the cavity mode are determined. Uniaxial strain on the order of 10−4 is introduced to tune the mode splitting. The mode splitting can be linearly tuned by the uniaxial strain, which agrees very well with theoretical calculations using a Jones matrix approach. We demonstrate that the RDS is a powerful, nondestructive tool to study the cavity anisotropy of VCSELs.
Show PACS
42.60.Fc Modulation, tuning, and mode locking
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Improved two level model of mid-infrared quantum cascade lasers for analysis of direct intensity modulation response

J. F. Webb and M. K. Haldar

J. Appl. Phys. 111, 043110 (2012); http://dx.doi.org/10.1063/1.3684660 (5 pages)

Online Publication Date: 23 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The direct intensity modulation response of quantum cascade lasers can be accurately calculated from a three-level model. However, the calculations are algebraically complex. An alternative two-level model gives simpler expressions and more readily provides insight into the role of parameters influencing the modulation response. The object of this paper is to improve the two-level model and analyze the direct intensity modulation response. The modified model will simplify theoretical investigation of modulation related phenomena.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Low-order harmonic generation in metal ablation plasmas in nanosecond and picosecond laser regimes

M. López-Arias, M. Oujja, M. Sanz, R. A. Ganeev, G. S. Boltaev, N. Kh. Satlikov, R. I. Tugushev, T. Usmanov, and M. Castillejo

J. Appl. Phys. 111, 043111 (2012); http://dx.doi.org/10.1063/1.3686740 (7 pages) | Cited 2 times

Online Publication Date: 23 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Low-order harmonics, third and fifth, of IR (1064 nm) laser emission have been produced in laser ablation plasmas of the metals manganese, copper and silver. The harmonics were generated in a process triggered by laser ablation followed by frequency up-conversion of a fundamental laser beam that propagates parallel to the target surface. These studies were carried out in two temporal regimes by creating the ablation plasma using either nanosecond or picosecond pulses and then probing the plasma plume with pulses of the same duration. The spatiotemporal behavior of the generated harmonics was characterized and reveals the distinct composition and dynamics of the plasma species that act as nonlinear media, allowing the comparison of different processes that control the generation efficiency. These results serve to guide the choice of laser ablation plasmas to be used for efficient high harmonic generation of laser radiation.
Show PACS
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.79.Nv Optical frequency converters
42.65.Re Ultrafast processes; optical pulse generation and pulse compression
52.38.Mf Laser ablation

Fast electro-optics of a single self-assembled quantum dot in a charge-tunable device

Jonathan H. Prechtel, Paul A. Dalgarno, Robert H. Hadfield, Jamie McFarlane, Antonio Badolato, Pierre M. Petroff, and Richard J. Warburton

J. Appl. Phys. 111, 043112 (2012); http://dx.doi.org/10.1063/1.3687375 (7 pages)

Online Publication Date: 29 February 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The response of a single InGaAs quantum dot, embedded in a miniaturized charge-tunable device, to an applied GHz bandwidth electrical pulse is investigated via its optical response. Quantum-dot response times of 1.0 ± 0.1 ns are characterized via several different measurement techniques, demonstrating GHz-bandwidth electrical control. Furthermore, a novel optical detection technique based on resonant electron-hole pair generation in the hybridization region is used to map fully the voltage pulse experienced by the quantum dot, showing, in this case, a simple exponential rise.
Show PACS
85.30.De Semiconductor-device characterization, design, and modeling
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close