Magnetically Mediated Transparent Conductors: In2_2O3_3 doped with Mo

First-principles band structure investigations of the electronic, optical and magnetic properties of Mo-doped In$_2$O$_3$ reveal the vital role of magnetic interactions in determining both the electrical conductivity and the Burstein-Moss shift which governs optical absorption. We demonstrate the advantages of the transition metal doping which results in smaller effective mass, larger fundamental band gap and better overall optical transmission in the visible -- as compared to commercial Sn-doped In$_2$O$_3$. Similar behavior is expected upon doping with other transition metals opening up an avenue for the family of efficient transparent conductors mediated by magnetic interactions

High-efficiency heteroepitaxial InP solar cells

High-efficiency, thin-film InP solar cells grown heteroepitaxially on GaAs and Si single-crystal bulk substrates are being developed as a means of eliminating the problems associated with using single-crystal InP substrates. A novel device structure employing a compositionally graded Ga(x)In(1-x)As layer between the bulk substrate and the InP cell layers is used to reduce the dislocation density and improve the minority carrier properties in the InP. The structures are grown in a continuous sequence of steps using computer-controlled atmospheric pressure metalorganic vapor phase epitaxy (APMOVPE). Dislocation densities as low as 3 x 10(exp 7) sq cm and minority carrier lifetimes as high as 3.3 ns are achieved in the InP layers with this method using both GaAs or Si substrates. Structures prepared in this fashion are also completely free of microcracks. These results represent a substantial improvement in InP layer quality when compared to heteroepitaxial InP prepared using conventional techniques such as thermally cycled growth and post-growth annealing. The present work is is concerned with the fabrication and characterization of high-efficiency, thin-film InP solar cells. Both one-sun and concentrator cells were prepared for device structures grown on GaAs substrates. One-cell cells have efficiencies as high as 13.7 percent at 25 C. However, results for the concentrator cells are emphasized. The concentrator cell performance is characterized as a function of the air mass zero (AM0) solar concentration ratio and operating temperature. From these data, the temperature coefficients of the cell performance parameters are derived as a function of the concentration ratio. Under concentration, the cells exhibit a dramatic increase in efficiency and an improved temperature coefficient of efficiency. At 25 C, a peak conversion efficiency of 18.9 percent is reported. At 80 C, the peak AM0 efficiency is 15.7 percent at 75.6 suns. These are the highest efficiencies yet reported for InP heteroepitaxial cells. Approaches for further improving the cell performance are discussed

InP concentrator solar cells for space applications

The design, fabrication, and characterization of high-performance, n(+)/p InP shallow-homojunction (SHJ) concentrator solar cells is described. The InP device structures were grown by atmospheric-pressure metalorganic vapor phase epitaxy (APMOVPE). A preliminary assessment of the effects of grid collection distance and emitter sheet resistance on cell performance is presented. At concentration ratios of over 100, cells with AM0 efficiencies in excess of 21 percent at 25 C and 19 percent at 80 C are reported. These results indicate that high-efficiency InP concentrator cells can be fabricated using existing technologies. The performance of these cells as a function of temperature is discussed, and areas for future improvement are outlined

InP/Ga0.47In0.53As monolithic, two-junction, three-terminal tandem solar cells

The work presented has focussed on increasing the efficiency of InP-based solar cells through the development of a high-performance InP/Ga(0.47)In(0.53)As two-junction, three-terminal monolithic tandem cell. Such a tandem is particularly suited to space applications where a radiation-hard top cell (i.e., InP) is required. Furthermore, the InP/Ga(0.47)In(0.53)As materials system is lattice matched and offers a top cell/bottom cell bandgap differential (0.60 eV at 300 K) suitable for high tandem cell efficiencies under AMO illumination. A three-terminal configuration was chosen since it allows for independent power collection from each subcell in the monolithic stack, thus minimizing the adverse impact of radiation damage on the overall tandem efficiency. Realistic computer modeling calculations predict an efficiency boost of 7 to 11 percent from the Ga(0.47)In(0.53)As bottom cell under AMO illumination (25 C) for concentration ratios in the 1 to 1000 range. Thus, practical AMO efficiencies of 25 to 32 percent appear possible with the InP/Ga(0.47)In(0.53)As tandem cell. Prototype n/p/n InP/Ga(0.47)In(0.53)As monolithic tandem cells were fabricated and tested successfully. Using an aperture to define the illuminated areas, efficiency measurements performed on a non-optimized device under standard global illumination conditions (25 C) with no antireflection coating (ARC) give 12.2 percent for the InP top cell and 3.2 percent for the Ga(0.47)In(0.53)As bottom cell, yielding an overall tandem efficiency of 15.4 percent. With an ARC, the tandem efficiency could reach approximately 22 percent global and approximately 20 percent AMO. Additional details regarding the performance of individual InP and Ga(0.47)In(0.53)As component cells, fabrication and operation of complete tandem cells and methods for improving the tandem cell performance, are also discussed

Monolithic InP/Ga0.47In0.53As tandem solar cells for space

A review is provided of progress made in the development of InP/Ga(0.47)In(0.53)As monolithic tandem solar cells since the last SPRAT conference. Improved one-sun, three terminal tandem designs have resulted in Air Mass Zero (AM0) efficiencies as high as 23.9 pct. at 25 C. Additionally, high efficiency concentrator versions of the three terminal device were developed. The best concentrator tandem has a peak AM0 efficiency of 28.8 pct. under 40.3 suns at 25 C. For the concentrator tandems, the subcell performance parameter temperature coefficients are reported as a function of the concentration ratio. Results from a computer modeling study are presented which provide a clear direction for improving the efficiency of the concentrator tandem. The prospects for fabricating high efficiency, series connected (i.e., two terminal) InP/Ga(0.47)In(0.53)As monolithic tandem cells are also discussed

MVDR broadband beamforming using polynomial matrix techniques

This paper presents initial progress on formulating minimum variance distortionless response (MVDR) broadband beamforming using a generalised sidelobe canceller (GSC) in the context of polynomial matrix techniques. The quiescent vector is defined as a broadband steering vector, and we propose a blocking matrix design obtained by paraunitary matrix completion. The polynomial approach decouples the spatial and temporal orders of the filters in the blocking matrix, and decouples the adaptive filter order from the construction of the blocking matrix. For off-broadside constraints the polynomial approach is simple, and more accurate and considerably less costly than a standard time domain broadband GSC

Assessment of Physical, Technical, and Tactical Analysis in the Australian Football League: A Systematic Review.

BACKGROUND: Elite Australian Football (AF) match-play requires proficiency in physical, technical, and tactical elements. However, when analysing player movement practitioners commonly exclude technical and tactical considerations, failing to recognise the multifactorial nature of AF match-play and providing little context into the movement requirements of the players. OBJECTIVES: This systematic review aimed to identify the physical, technical, and tactical requirements of the Australian Football League (AFL) and to highlight the importance of integrating data from multiple sources when analysing player output. METHODS: A systematic search of electronic databases (CINAHL, PubMed, Scopus, SPORTDiscus, and Web of Science) was conducted from January 2009 to June 2022. Keywords relating to physical, technical, and tactical match requirements were used. RESULTS: Forty-eight studies met the inclusion criteria. In isolation, physical requirements were the most analysed construct within the AFL (n = 17), followed by technical (n = 9) and then tactical (n = 6). Thirteen studies integrated physical and technical elements, one study integrated technical and tactical elements, one study integrated physical and tactical elements, and one study integrated all three elements. Movement analysis centred around average 'whole' match requirements, whereas technical and tactical match analyses focused on key performance indicators of match performance. CONCLUSION: While the physical requirements of the AFL have been well documented, there is little understanding of how player technical output and various team tactics influence player movement requirements. Knowledge of how the elements of AF match-play interact with one another could enhance our understanding of match performance and provide a greater resource for training prescription

The use of hyperspectral imaging for cake moisture prediction

In this paper, hyperspectral imaging is demonstrated to be a valid method for predicting the moisture content of baked sponge cakes. The application of this technology in the cake production environment, empowered by sophisticated signal & image processing techniques and prediction algorithms has the potential to provide on-line, real-time, non-destructive cake moisture monitoring

Combining high conductivity with complete optical transparency: A band-structure approach

A comparison of the structural, optical and electronic properties of the recently discovered transparent conducting oxide (TCO), nanoporous Ca12Al14O33, with those of the conventional TCO's (such as Sc-doped CdO) indicates that this material belongs conceptually to a new class of transparent conductors. For this class of materials, we formulate criteria for the successful combination of high electrical conductivity with complete transparency in the visible range. Our analysis suggests that this set of requirements can be met for a group of novel materials called electrides.Comment: 3 pages, 3 figures, submitted for publicatio