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Description
This dissertation addresses challenges pertaining to multi-junction (MJ) solar cells from material development to device design and characterization. Firstly, among the various methods to improve the energy conversion efficiency of MJ solar cells using, a novel approach proposed recently is to use II-VI (MgZnCd)(SeTe) and III-V (AlGaIn)(AsSb) semiconductors lattice-matched on GaSb or InAs substrates for current-matched subcells with minimal defect densities. CdSe/CdTe superlattices are proposed as a potential candidate for a subcell in the MJ solar cell designs using this material system, and therefore the material properties of the superlattices are studied. The high structural qualities of the superlattices are obtained from high resolution X-ray diffraction measurements and cross-sectional transmission electron microscopy images. The effective bandgap energies of the superlattices obtained from the photoluminescence (PL) measurements vary with the layer thicknesses, and are smaller than the bandgap energies of either the constituent material. Furthermore, The PL peak position measured at the steady state exhibits a blue shift that increases with the excess carrier concentration. These results confirm a strong type-II band edge alignment between CdSe and CdTe. The valence band offset between unstrained CdSe and CdTe is determined as 0.63 eV±0.06 eV by fitting the measured PL peak positions using the Kronig-Penney model. The blue shift in PL peak position is found to be primarily caused by the band bending effect based on self-consistent solutions of the Schrödinger and Poisson equations. Secondly, the design of the contact grid layout is studied to maximize the power output and energy conversion efficiency for concentrator solar cells. Because the conventional minimum power loss method used for the contact design is not accurate in determining the series resistance loss, a method of using a distributed series resistance model to maximize the power output is proposed for the contact design. It is found that the junction recombination loss in addition to the series resistance loss and shadowing loss can significantly affect the contact layout. The optimal finger spacing and maximum efficiency calculated by the two methods are close, and the differences are dependent on the series resistance and saturation currents of solar cells. Lastly, the accurate measurements of external quantum efficiency (EQE) are important for the design and development of MJ solar cells. However, the electrical and optical couplings between the subcells have caused EQE measurement artifacts. In order to interpret the measurement artifacts, DC and small signal models are built for the bias condition and the scan of chopped monochromatic light in the EQE measurements. Characterization methods are developed for the device parameters used in the models. The EQE measurement artifacts are found to be caused by the shunt and luminescence coupling effects, and can be minimized using proper voltage and light biases. Novel measurement methods using a pulse voltage bias or a pulse light bias are invented to eliminate the EQE measurement artifacts. These measurement methods are nondestructive and easy to implement. The pulse voltage bias or pulse light bias is superimposed on the conventional DC voltage and light biases, in order to control the operating points of the subcells and counterbalance the effects of shunt and luminescence coupling. The methods are demonstrated for the first time to effectively eliminate the measurement artifacts.
ContributorsLi, Jingjing (Author) / Zhang, Yong-Hang (Thesis advisor) / Tao, Meng (Committee member) / Schroder, Dieter (Committee member) / Vasileska, Dragica (Committee member) / Arizona State University (Publisher)
Created2012
Description
Only in recent decades have music libraries become more aware of the importance of preservation of musical scores and materials in their collections. It follows that the preservation goals in a library differ from those in a museum due to the specific purpose of the collecting institution. As a student of paper conservation in an art museum setting and a musician with classical training, I wanted to investigate the scope of art conservation as it applies to cultural heritage objects outside the realm of works of visual art in a museum—namely the musical scores and ephemera contained in the Bavicchi archive in the ASU Music Library Special Collections. The archive is a large, unexplored collection of materials pertaining to approximately ninety opuses composed by the teacher, conductor, and composer, John A. Bavicchi (1922-2012). These materials include final scores, drafts of scores, preliminary sketches, programs from performances, correspondence, news publications, publishing agreements, and financial records. Although these types of ephemera materials are transitory by nature and pose considerable problems for the institution responsible for their preservation, the goal of this project is to demonstrate the importance of preserving non-art objects related to non-visual artforms in a music library context, to show the value of musical ephemera in general, and to advocate for the care of the Bavicchi archive in particular. Using one Bavicchi composition, Opus 51, as a case study from which to develop a protocol for the preservation of the rest of the archive, I made an inventory of all seventy-four objects pertaining to Opus 51, executed and documented conservation treatment, and implemented proper housing for all objects. Making sure to consider how and where these archival materials are most likely to be used—for scholarly research in a music library—I established guidelines for evaluating condition and assigning treatment priority, provided descriptions of relevant remedial treatment procedures, and recommended rehousing and potential preservation practices. Additionally, I offered justification for my conservation work through the contextualization of the archival materials relating to Opus 51. I provided an initial musical analysis of the archival materials and compared the informational content of the Opus 51 ephemera to general information gathered from outside sources, with the intention of illustrating the need to preserve these materials in order to better understand Bavicchi’s compositional process and the public reception of his work.
ContributorsTuijl-Goode, Remi (Author) / Saucier, Catherine (Thesis director) / Mossman Tepper, Dana (Thesis director) / Mehrens, Christopher (Committee member) / Barrett, The Honors College (Contributor) / School of Art (Contributor) / School of Music, Dance and Theatre (Contributor) / School of Molecular Sciences (Contributor)
Created2022-12
Description
This project discusses the horn, tuba, piano sub-genre of brass chamber music. Alec Wilder wrote the first piece for this instrumentation in 1963 for his friends John Barrows and Harvey Phillips. Wilder's compositional style was directly affected by life events and relationships. Through letters, biographies, recordings and autobiographies the importance of his friendship with Barrows and Phillips are displayed to show the links between the two men and the composer's compositional output. A deeper look into the life of Alec Wilder and a thematic analysis of his Suite No.1 for Horn, Tuba and Piano (1963), and Suite No.2 for Horn, Tuba and Piano (1971) shed light on the beginnings of the genre and provide a deeper understanding of the works. Since Wilder's two trios there have been at least twenty works written for this instrumentation. A brief overview of works written for the trio since 1971 provide a broad sense of the quantity and benefits of the trio in the hopes of inspiring new performances and compositions. This paper will combine the seemingly random compositions for the instrumentation into a collected repertoire. With an increase in exposure, the trio for horn, tuba and piano has the potential to become a standard brass chamber group that will benefit students, performers, and audiences alike.
ContributorsRomano, Christina Marie (Author) / Ericson, John Q (Thesis advisor) / Saucier, Catherine (Committee member) / Swoboda, Deanna (Committee member) / Arizona State University (Publisher)
Created2015
Description
In 1808, Heinrich Domnich (1767-1844) published his book, Méthode de Premier et de Second Cor, in which he credited the invention of hand horn to Dresden hornist Anton Joseph Hampel (1710-1771). The notion that Hampel was the first horn player to experiment and teach hand horn technique has persisted to the present day. This assumption disregards evidence found in Telemann's compositions and Baroque instrument design, where hand horn technique was clearly in use before Hampel.
This paper presents evidence that before Hampel, hand horn was in use and called for by composers. Because of the number of works for horn he generated before and during Hampel's life, Telemann's pieces provide powerful insight into the use of Baroque horn. Musical examples originate from passages in Telemann's works where the horn performs in a solo capacity and the music requires the performer to produce pitches outside the harmonic series. By necessity, the performer must use either the hand or bend the note with the embouchure in order to produce the correct pitch with the hand being the logical choice. The paper also examines published interviews from horn pedagogues, history books, method books from the classical and baroque eras, baroque and hand horn design, as well as articles written by some of the world's foremost baroque and hand horn experts.
By indentifying the number of non harmonic series tones in Telemann's music, combined with the opinions of hand horn experts, this paper suggests that horn players during the Baroque era must have known about, and used, hand horn technique. This knowledge will influence performer's interpretation of baroque pieces by providing a more historically informed performance, clearer understanding of intonation, the variety of tone colors expected, and create a better understanding of the development of the horn from foxhunting to the concert hall.
This paper presents evidence that before Hampel, hand horn was in use and called for by composers. Because of the number of works for horn he generated before and during Hampel's life, Telemann's pieces provide powerful insight into the use of Baroque horn. Musical examples originate from passages in Telemann's works where the horn performs in a solo capacity and the music requires the performer to produce pitches outside the harmonic series. By necessity, the performer must use either the hand or bend the note with the embouchure in order to produce the correct pitch with the hand being the logical choice. The paper also examines published interviews from horn pedagogues, history books, method books from the classical and baroque eras, baroque and hand horn design, as well as articles written by some of the world's foremost baroque and hand horn experts.
By indentifying the number of non harmonic series tones in Telemann's music, combined with the opinions of hand horn experts, this paper suggests that horn players during the Baroque era must have known about, and used, hand horn technique. This knowledge will influence performer's interpretation of baroque pieces by providing a more historically informed performance, clearer understanding of intonation, the variety of tone colors expected, and create a better understanding of the development of the horn from foxhunting to the concert hall.
ContributorsGilbert, Joel Gregory (Author) / Ericson, John Q (Thesis advisor) / Swoboda, Deanna (Committee member) / Saucier, Catherine (Committee member) / Arizona State University (Publisher)
Created2014