Control Device Performance Research Articles

Self-amplified spontaneous emission free electron laser devices and nonideal electron beam transport

We have developed, at the SPARC test facility, a procedure for a real time self-amplified spontaneous emission free electron laser (FEL) device performance control. We describe an actual FEL, including electron and optical beam transport, through a set of analytical formulas, allowing a fast and reliable on-line ``simulation'' of the experiment. The system is designed in such a way that the characteristics of the transport elements and the laser intensity are measured and adjusted, via a real time computation, during the experimental run, to obtain an on-line feedback of the laser performances. The detail of the procedure and the relevant experimental results are discussed.

A benzodithiophene-based novel electron transport layer for a highly efficient polymer solar cell.

We designed and synthesized a novel conjugated polyelectrolyte (CPE), poly{3-[2-[4,8-bis(2-ethyl-hexyloxy)-6-methyl-1,5-dithia-s-indacen-2-yl]-9-(3-dimethylamino-propyl)-7-methyl-9H-fluoren-9-yl]-propyl}-dimethyl-amine (PBN). We employed PBN as an electron-transporting layer on a ZnO layer and constructed a highly efficient, inverted structure device consisting of a mixture of poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7) and PC70BM, achieving a high power conversion of up to 8.6%, constituting a 21.1% improvement over the control device performance (7.1%) prepared without a PBN layer. This result was ascribed to the reduced interfacial resistance and the improved charge transport and collection through the PBN electron transport layer.

Facial fat grafting with a prototype injection control device

ObjectiveTo evaluate the initial clinical performance of a prototype injection control device (ICD) to facilitate fat grafting by injection.MethodsAn ICD, which mechanically couples the act of withdrawing the cannula with the act of depressing the plunger, was fabricated for the purpose of facial fat grafting. The action of the device results in deposition of consistent threads of fat having a volume of approximately 33 uL per cm that the cannula is withdrawn, which is slightly less than the internal volume of a 12-gauge cannula. A total of 26 patients underwent 30 procedures, and the results were subjectively evaluated using pre- and postoperative photographs, with a minimum follow-up of 4 months.ResultsThe desired degree of correction was more consistent, recovery was faster, and procedural efficiency was improved when performing the procedure with the ICD compared to historical use of the manual method of injection. Minor irregularities were the only complications encountered.ConclusionThe ICD optimally distributes fat as a uniform thread along the withdrawal tract of the cannula, thereby eliminating clumping and minimizing tissue trauma, resulting in reduced recovery time as well as more consistent and predictable clinical results. Since the ICD automates the injection process, it provides a notable and easily attainable efficiency in procedural time and minimal learning curve for the user.

Nanoscale Engineering of Exciton Dissociating Interfaces in Organic Photovoltaics

Interfaces are inherent in and essential to organic electronic devices. At every interface, both organic/organic and organic/inorganic, the potential to utilize nanostructuring to control device performance is very high. In this paper, we focus on one example of nanostructuring at the donor/acceptor heterojunction in organic photovoltaics, with the purpose of modifing efficiency by four orders of magnitude. We show that the length of the exciton dissociating interface can be tuned by changing the substrate temperature for small molecule heterojunction photodiodes based on crystalline DIP/C60 mixtures. Due to the tuneable interface morphology, the performance of such devices can be changed from poor performing planar heterojunctions to higher efficiency ordered nanoscale bulk heterojunction structures. In this way, highly crystalline DIP can be thought of as a natural “bulk” heterojunction.

Nanoscale Engineering of Exciton Dissociating Interfaces in Organic Photovoltaics

Interfaces are inherent in and essential to organic electronic devices. At every interface, both organic/organic and organic/inorganic, the potential to utilize nanostructuring to control device performance is very high. In this paper, we focus on one example of nanostructuring at the donor/acceptor heterojunction in organic photovoltaics, with the purpose of modifing efficiency by four orders of magnitude. We show that the length of the exciton dissociating interface can be tuned by changing the substrate temperature for small molecule heterojunction photodiodes based on crystalline DIP/C60 mixtures. Due to the tuneable interface morphology, the performance of such devices can be changed from poor performing planar heterojunctions to higher efficiency ordered nanoscale bulk heterojunction structures. In this way, highly crystalline DIP can be thought of as a natural “bulk” heterojunction.

The effect of various electrodes on the properties of electroluminescent devices with potassium chloride inside tris (8-hydroxyquinoline) aluminum

The performance of organic light-emitting diodes (OLED), based on NPB/Alq 3/KCl/Alq 3 active regions, with various anode (i.e. ITO and ITO/MoO 3) and cathode (i.e. Al and LiF/Al) structures is compared. NPB, Alq 3, KCl, ITO, MoO 3, Al and LiF are N,N′-bis-(1-naphthl)-diphenyl-1,1′-biphenyl-4,4′-diamine, tris (8-hydroxyquinoline) aluminum, potassium chloride, indium-tin oxide, molybdenum trioxide, aluminum and lithium fluoride, respectively. When bare Al is used as a cathode, both luminance and efficiency are improved by the insertion of KCl inside Alq 3 ( anode/NPB/Alq 3/KCl/Alq 3/Al), compared to a control device ( anode/NPB/Alq 3/Al). This is attributed to trap sites induced by KCl layer, which give a better recombination in the devices. However, if the cathode is LiF/Al, the performance of control device ( anode/NPB/Alq 3/LiF/Al) is superior to that of devices with KCl inside Alq 3 ( anode/NPB/Alq 3/KCl/Alq 3/LiF/Al), which is attributed that the probability of electron injection from cathode is decreased.

Temperature dependent model dielectric function of highly disordered Ga0.52In0.48P

We report on the temperature dependence of the dielectric function of Ga0.52In0.48P from room temperature to 500°C, and for photon energies from 0.75eV to 5eV. The undoped, highly disordered Ga0.52In0.48P thin film was grown by metal-organic vapor phase epitaxy lattice matched onto a (001) GaAs substrate. The dielectric function of Ga0.52In0.48P was measured by in-situ spectroscopic ellipsometry, and analyzed using Adachi's composite critical point model. We provide a second-order temperature expansion parameter set for calculation of the Ga0.52In0.48P dielectric function and its temperature dependence, and which may become useful for in situ growth control or optoelectronic device performance evaluation at elevated temperatures. We discuss the temperature-induced shift of critical point transition energy parameters.

Non-Contact and Non-Destructive Characterization Alternatives of Ultra-Shallow Implanted Silicon p-n Junctions by Multi-Wavelength Raman and Photoluminescence Spectroscopy

Ultra-shallow boron implanted ( ) n-type Si wafers were prepared and characterized by multi-wavelength Raman and photoluminescence (PL) spectroscopy before and after rapid thermal annealing (RTA). The Raman and PL characterization results were compared with sheet resistance from four point probe measurements and boron depth profiles from secondary ion mass spectroscopy. We have found a very strong correlation between the rapid, non-contact optical characterization results and important parameters of ultra-shallow junctions (USJs) obtained from conventional invasive techniques. Ultraviolet Raman was very sensitive to subsurface B profiles near or above the solid solubility of B in Si. Visible wavelength excitation PL indicated the presence of significant levels of nonradiative recombination centers beyond the USJ depth and implant end-of-range damage even after RTA. Multi-wavelength Raman and PL are found to be very promising as complementary and/or alternative diagnostic metrology tools for implant process control and in-line device performance screening.

Isothermal microcalorimetry perfusion experiments: A method to verify the relative vapour pressure of organic liquids inside the sample vessel

Perfusion microcalorimetry is frequently applied to expose pharmaceutical solids to specific relative vapour pressures (RVP) of organic liquids or water. The aim was to set up a general procedure to check the performance of a vapour pressure control device used to create a specific RVP. This was achieved by identifying and checking the significant factors in the creation of the RVP inside the reaction vessel. The flow switch valve was tested by volume flow measurements whereas the saturation of the wet line was verified in a calorimetric experiment employing methanol as model solvent. The results of the measurements were used to calculate the RVP inside the reaction vessel. The method developed is suitable to test the vapour pressure control device. It can be applied for any solvent.

Toward High-Performance Amorphous GIZO TFTs

This work analyzes the role of processing parameters on the electrical performance of GIZO films and thin-film transistors (TFTs). Parameters such as oxygen partial pressure, deposition pressure, target composition, thickness, and annealing temperature are studied. Generally, better devices are obtained when low oxygen partial pressure is used. This is related to the damage induced by oxygen ion bombardment and very high film’s resistivity when higher oxygen partial pressures are used. Low deposition pressures and targets with richer indium compositions led to films with high carrier concentration, resulting in transistors with field-effect mobility as high as but poor channel conductivity modulation, becoming ineffective as switching devices. Nevertheless, it is demonstrated that reducing the GIZO thickness from greatly enhances the switching behavior of those devices, due to the lower absolute number of free carriers and hence to their easier depletion. Annealing also proves to be crucial to control device performance, significantly modifying GIZO electrical resistivity and promoting local atomic rearrangement, being the optimal temperature determined by the as-produced films’ properties. For the best-performing transistors, even with a low annealing temperature , remarkable properties such as , on∕off , , and are achieved.

A urinary control device for management of female stress incontinence

Objective: To examine the performance of a silicon urinary control device for nonsurgical management of women with genuine stress incontinence. Methods: A 3-month prospective study involved 41 women with genuine stress incontinence. They completed urinary diaries of voiding, incontinence, and severity of incontinence on a 4-point scale over a week. Subjects were taught how to apply the device and used it as required from the second week. Visual analogue scales were used to record aspects of use (such as acceptability, comfort, and ease of application), and 2-hour perineal pad tests were completed at recruitment, after 2 weeks, and after 3 months. Data were compared by Mann-Whitney U test, or Wilcoxon test. Results: Ten women (24.4%) declined to participate and six (14.6%) withdrew before 2 weeks. Ten (24.4%) failed to attend for 2-week follow-up and 11 (26.8%) did not continue for 3 months. Two (4.9%) did not attend 3-month follow-up. Only two women (4.9%) completed the study. There was no difference in pad test results or in results from voiding diaries. Conclusion: The urinary incontinence device had low acceptability and was ineffective, and we cannot recommend it for nonsurgical management of genuine stress incontinence.

The effect of substrates on the transverse geometry photorefractive thin films

Although photorefractive thin films in the transverse geometry retain most of the basic features of the bulk photorefractive materials, the abrupt changes in the dielectric constant across the boundary regions always accompany polarized charge gratings. These gratings are generated by the perpendicular component of the space charge field and they are absent in the bulk transport equations. Our systematic theoretical calculation indicates that these boundary charge gratings will strongly influence device performance. Adjustment of the dielectric properties of media sandwiching the thin film can serve as a method by which control device performance.

Experimental and Theoretical Analysis of the above Threshold Characteristics of Amorphous Silicon Alloy Field Effect Transistors

AbstractExperimental studies on the above threshold characteristics of amorphous silicon alloy thin films transistors show that the field-effect mobility has a weak temperature dependence and that the current-voltage characteristics are described by a power law dependence on gate voltage, with an exponent greater than two. These results are in good agreement with our theoretical model, which demonstrates that in the above threshold regime, the Fermi level at the semiconductor-insulator interface lies in the tail states which control device performance. Analysis of the above threshold characteristics shows the characteristic energy variation of the exponential tail state distribution to be ∼22meV and that the on current changes by a factor of only two over the temperature range lO−90°C.

On the electrical properties of the I2L n-p-n transistor

The optimization of the I <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> L speed-power product requires a clear understanding of the physical mechanisms that control device performance. Test structures have been designed and fabricated to characterize both intrinsic and extrinsic elements of an I <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> L gate. The electrical properties of the intrinsic n-p-n transistor are compared to calculations. Good agreement between measured and calculated beta is obtained for both the up and down transistor without parametric fitting. Band shrinkage, degeneracy, and Auger recombination are found to be important factors in determining the n-p-n base current. Intrinsic up betas greater than 2000 have been measured. The importance of n-p-n beta on the unit cell effective beta and the gate switching time is discussed.