VictorJuiz/thesis huggingface dataset:
Physics and technology of tensile-strained germanium for high-performance silicon-compatible optoelectronics [electronic resource]

Modern high-bandwidth communications systems primarily use optical links to support data transmission across a range of length scales, from metro/long-haul for infrastructure backbones to shorter-range cables in data centers. As performance, cost, and energy-efficiency requirements become more demanding, optical links are expected to eventually supplant copper-based interconnects at the board-to-board, chip-to-chip, and on-chip levels as well. Most optoelectronic devices use III-V materials to achieve high performance. Though efficient, these materials are expensive, toxic, and incompatible with the standard high-volume silicon-based manufacturing used to build microprocessors. In order for the transition to optics to take place at the smaller length scales, a fully silicon-compatible photonics technology is needed to replace the III-Vs and allow us to leverage the practical advantages of silicon-based manufacturing. This dissertation presents a foundational set of new platform technologies that make major improvements to the current state of silicon-compatible optoelectronics research. In the first part, we present the development of a new method for manufacturing germanium--on--insulator substrates, an attractive materials platform for optical devices. In the second part of the dissertation, we introduce a new silicon-compatible platform technology that can be used to dramatically enhance the optical performance of germanium-based light emitters and detectors.

Keywords: Electrical Engineering
Advisor: Howe Roger Thomas primary advisor. Thesis advisor
Brongersma Mark L. advisor. Thesis advisor
Miller D. A. B. advisor. Thesis advisor
Pivot thinking and the differential sharing of information within new product development teams [electronic resource]

Functionally diverse team members bring unique sets of cognitive styles to team interaction; it is less clear how these differences affect the exchange of critical, mutually required team information. This cognitive diversity in new product design (NPD) teams increases the likelihood that individual team members will perceive the team's task differently, leading to "cognitive representational gaps" between teammates' interpretations of both the task and potential solution. This research shows that cognitively diverse NPD teams develop representational gaps based on individual cognitive preferences between convergent and divergent information types and these cognitive preferences influence both task definition and solution. A second experiment shows that team leadership that bridges cognitive preferences, called "pivot thinking, " can overcome this limiting behavior. Understanding these general mechanisms deepens understanding of group information processing and conflict in cognitively diverse NPD teams. Implications for design education are discussed.

Keywords: Mechanical Engineering
Advisor: Leifer Larry J. primary advisor. Thesis advisor
Hinds Pamela advisor. Thesis advisor
Shavelson Richard J.
Plasmonic optical antennas for enhanced light detection and emission [electronic resource]

Antennas are used across a wide range of frequencies in the electromagnetic spectrum to concentrate wave energy into electronic circuits. The principles that govern the operation of conventional radio-frequency antennas can be extended to much higher frequencies and be applied to produce nano-metallic (i.e. plasmonic) antennas that act as "receivers" and "transmitters" for visible light. These traits make them excellent candidates for light trapping in solar cells, light concentration in sub-wavelength photodetectors, or even localized heating for cancer therapies. The unique optical properties of metals at visible frequencies make it difficult to apply traditional antenna design rules. Using full-field electromagnetic simulations and analytical antenna models, we developed new design rules for producing optical antennas with a desired set of optical properties. We then applied these design rules to create antennas that resonantly enhance absorption on thin silicon detectors as well as enhance emission of cathodoluminescence (CL). Through spatial and spectral mapping of both photocurrent and CL we clearly show the fundamental and higher-order resonant modes of these antennas. With CL we are also able to map the spatial distribution of these resonant modes with nanometer resolution. In addition to these specific demonstrated applications, the results of this work enable optical engineers to more easily design a myriad of plasmonic devices that employ optical antenna structures, including nanoscale photodetectors, light sources, sensors, and modulators.

Keywords: Materials Science and Engineering
Advisor: Brongersma Mark L. primary advisor. Thesis advisor
Fan Shanhui
Salleo Alberto
The political economy of anti-poverty programs in Indonesia [electronic resource]

This dissertation consists of three papers: 1) Targeting the Poor: Evidence from a Field Experiment in Indonesia; 2) Do Village Politics Matter?: Evidence from a Natural Experiment on the Distribution of a Cash Transfer in Indonesia; and 3) Assessing the Political Impacts of a Conditional Cash Transfer: Evidence from a Randomized Policy Experiment in Indonesia. The papers collectively explore several different aspects of the political economy of anti-poverty programs in Indonesia. In the first paper, a randomized experiment compares different methods of targeting an unconditional cash transfer to poor households. By testing the effectiveness of community-based methods versus government-centered methods on community satisfaction and accuracy in reaching the poor, the paper addresses several important questions relevant to the political economy of development and decentralization. The second paper analyzes the extent to which the distribution of Indonesia's unconditional cash transfer -- the world's largest cash transfer program to date -- is influenced by local political factors. Using a natural experiment, I explore how the quasi-random timing of village head elections affects the distribution of benefits to poor and non-poor households. Finally, my third paper analyzes the political effects of a randomized conditional cash transfer (CCT) pilot program to test its impacts on support for incumbent politicians, political participation, and several other indicators relevant to local democracy.

Keywords: Political Science.
Advisor: Rodden Jonathan primary advisor. Thesis advisor
Magaloni Beatriz advisor. Thesis advisor
Weinstein Jeremy M. advisor. Thesis advisor
The political economy of publicly-provided goods [electronic resource]

This dissertation consists of three chapters which explore various aspects of the political economy of publicly-provided goods. I shed light on why governments do or do not invest in goods of different types, and also how government versus private provision affects consumers. What follows are three empirical analyses testing the implications of competing theoretical models. My first chapter addresses the question, what drives governments with similar revenues to publicly provide very different amounts of goods for which private substitutes are available? Key examples are education and health care. I compare spending by Brazilian municipalities on pre-primary education--a good that is also provided privately--with spending on public infrastructure like parks and roads, which lacks private substitutes. I find that municipalities with higher median income and more inequality are less likely to allocate revenue to education or to expand pre-primary enrollment. They are more likely to allocate revenue to public infrastructure. This seems to occur for two reasons. In rich and unequal municipalities, fewer total people support public education spending (the collective choice channel), and also, any given poor person wanting public education has less influence over policymakers there (the political power channel). My second chapter addresses the question, can private sector participation (PSP) in the urban piped water sector improve child health? A fixed effects analysis suggests that the introduction of PSP decreases diarrhea among under-five children by between 2.2 and 2.6 percentage points, or 14-16%. An instrumental variables analysis that uses variation in the share of the world water market controlled by former colonizing countries suggests that the effects are twice as large. The difference between the OLS and the IV results can be explained by the fact that PSP is more likely when the water sector is distressed and causing health problems. Importantly, PSP appears to benefit the health of children from the poorest households the most. It also leads to higher rates of reliance on piped water as the primary water source, which is a likely channel explaining child health improvements. My third chapter, joint with John Hatfield, examines how competition between governments affects economic growth. We find that doubling the number of local governments in a metropolitan area increases the income growth rate over 1969-2006 by 18%, which implies an approximate 900 difference in 2006 income. Decomposing this effect, we find that 60% stems from inter-jurisdictional competition changing the composition of the workforce, while 40% comes from making existing workers more productive. The results support a formal model showing that competition for capital drives local governments to provide productive public goods at levels which maximize economic growth (Hatfield 2010).

Advisor: Jayachandran Seema primary advisor. Thesis advisor
Jha Saumitra primary advisor. Thesis advisor
Hoxby Caroline Minter advisor. Thesis advisor
Wacziarg Romain advisor. Thesis advisor
The political economy of publicly-provided goods [electronic resource]

This dissertation consists of three chapters which explore various aspects of the political economy of publicly-provided goods. I shed light on why governments do or do not invest in goods of different types, and also how government versus private provision affects consumers. What follows are three empirical analyses testing the implications of competing theoretical models. My first chapter addresses the question, what drives governments with similar revenues to publicly provide very different amounts of goods for which private substitutes are available? Key examples are education and health care. I compare spending by Brazilian municipalities on pre-primary education--a good that is also provided privately--with spending on public infrastructure like parks and roads, which lacks private substitutes. I find that municipalities with higher median income and more inequality are less likely to allocate revenue to education or to expand pre-primary enrollment. They are more likely to allocate revenue to public infrastructure. This seems to occur for two reasons. In rich and unequal municipalities, fewer total people support public education spending (the collective choice channel), and also, any given poor person wanting public education has less influence over policymakers there (the political power channel). My second chapter addresses the question, can private sector participation (PSP) in the urban piped water sector improve child health? A fixed effects analysis suggests that the introduction of PSP decreases diarrhea among under-five children by between 2.2 and 2.6 percentage points, or 14-16%. An instrumental variables analysis that uses variation in the share of the world water market controlled by former colonizing countries suggests that the effects are twice as large. The difference between the OLS and the IV results can be explained by the fact that PSP is more likely when the water sector is distressed and causing health problems. Importantly, PSP appears to benefit the health of children from the poorest households the most. It also leads to higher rates of reliance on piped water as the primary water source, which is a likely channel explaining child health improvements. My third chapter, joint with John Hatfield, examines how competition between governments affects economic growth. We find that doubling the number of local governments in a metropolitan area increases the income growth rate over 1969-2006 by 18%, which implies an approximate 900 difference in 2006 income. Decomposing this effect, we find that 60% stems from inter-jurisdictional competition changing the composition of the workforce, while 40% comes from making existing workers more productive. The results support a formal model showing that competition for capital drives local governments to provide productive public goods at levels which maximize economic growth (Hatfield 2010).

Keywords: Business.
Advisor: Jayachandran Seema primary advisor. Thesis advisor
Jha Saumitra primary advisor. Thesis advisor
Hoxby Caroline Minter advisor. Thesis advisor
Wacziarg Romain advisor. Thesis advisor
Political origins of firm strategies [electronic resource]

What explains the emergence of different kinds of capitalist systems across advanced industrialized democracies? In particular, why do highly coordinated employer associations form in some states and not others, and why do such organizations change over time? Because different kinds of contemporary employer coordination or varieties of capitalism are linked to long-term outcomes of unemployment, inequality, social policy generosity, and product innovation, it is important to understand their historical origins and development. I propose a new theory of the development of highly coordinated employer associations and their absence in advanced industrialized states. I argue that the key decisions firms faced involved addressing the redistributive threat posed by the political organization of workers, and the collective action problem of organizing themselves. The cross-national and temporal variation in firm strategies depends on two variables: levels of industrial heterogeneity and the political mobilization of workers. The former affects the incentives of firms to act collectively or individually; the latter shapes their incentives to pursue a collaborative or repressive approach. This parsimonious framework accounts for a much wider range of variation in firm strategies. To test the theory I use extensive qualitative and quantitative evidence from the development of employer associations in Germany and the United States. I also test the portability of the theory with cross-national evidence. I conclude with discussion of broader implications for comparative politics, in particular the importance of understanding collective action among firms and instruments of repression.

Keywords: Political Science.
Advisor: Mares Isabela primary advisor. Thesis advisor
Rodden Jonathan primary advisor. Thesis advisor
Haber Stephen H.
Laitin David D. advisor. Thesis advisor
Political regimes and redistribution [electronic resource]

How do political institutions affect wealth redistribution initiatives and their efficacy? While influential current theory holds that redistribution should be both higher and more targeted at the poor under democracy, many newly democratic states have failed to implement redistributive policies that would benefit the majority of newly enfranchised voters. Using original data, primarily though not exclusively on land reform and bank and natural resource expropriations in Latin America, I find that redistribution has actually been greatest during periods of autocratic rule. I demonstrate empirically that where institutional constraints to rule are higher, as in democracy, large-scale redistribution is more difficult to implement. But why do some autocratic rulers choose to redistribute while others do not? I argue that when there is a split between a dictator's support coalition and elites out of government that can pose a threat to his rule, the dictator may choose to expropriate rival elites. Simultaneously redistributing much of the assets of those elites to the poor can gain the support of lower classes and reduce potentially destabilizing pressure from below. One important consequence is that dictators who have expropriated tend to survive longer in office than those that do not. Although redistribution is often more likely under autocracy, there are nonetheless cases of redistribution under democracy. When elites are politically weak during the democratic transition process, as during revolution, there is a long-run relationship between democracy and redistribution. So although democracy may sometimes be a credible commitment to redistribution, it is more often captured by elites and does not induce redistribution.

Keywords: Political Science
Advisor: Laitin David D. primary advisor. Thesis advisor
Fearon James D. advisor. Thesis advisor
Rodden Jonathan advisor. Thesis advisor
Politics makes strange bedfellows [electronic resource] : why political and industrial diversity helps contract lobby organizations retain clients and make money

Many studies examine why organizations are shaped by their institutional environment, but few seek to understand the process of organizations attempting to influence the government. This dissertation focuses on an industry dedicated to influencing elite members of the nation-state: contract lobby organizations. These companies serve clients by monitoring government for threats and opportunities, and then promoting or countering changes to the status quo. They do so through coalitions of politically and industrially affiliated lobbyists who engage with policymakers directly. There are two basic approaches to employing lobbyists. One is to specialize by having only one type (for example, only Republicans who specialize in the defense industry). The other is to generalize by having a team balanced across a diverse set of political and industrial categories. I examine these organizational structures to challenge the broadly held position that specialized organizations perform better relative to the generalists they compete with. Contrary to the common finding, this study reveals that a generalist approach is more useful for lobby organizations in terms of reducing failure and increasing revenue growth. This exception occurs because these organizations must engage a group constrained by a norm prescribing collective agreement. Diverse teams are better positioned to monitor the population as a whole by contacting a broad sample, increasing the validity of identified threats and opportunities. They are in a better position to influence the population of Congress members by recruiting observable champions to their cause who belong to several categories, amplifying the legitimacy of their issue and reducing the appearance of controversy. This mechanism establishes a link between the observed organizational structure and organizational performance.

Advisor: Barnett William A.
Hannan Michael
Rao Hayagreeva
Politics makes strange bedfellows [electronic resource] : why political and industrial diversity helps contract lobby organizations retain clients and make money

Many studies examine why organizations are shaped by their institutional environment, but few seek to understand the process of organizations attempting to influence the government. This dissertation focuses on an industry dedicated to influencing elite members of the nation-state: contract lobby organizations. These companies serve clients by monitoring government for threats and opportunities, and then promoting or countering changes to the status quo. They do so through coalitions of politically and industrially affiliated lobbyists who engage with policymakers directly. There are two basic approaches to employing lobbyists. One is to specialize by having only one type (for example, only Republicans who specialize in the defense industry). The other is to generalize by having a team balanced across a diverse set of political and industrial categories. I examine these organizational structures to challenge the broadly held position that specialized organizations perform better relative to the generalists they compete with. Contrary to the common finding, this study reveals that a generalist approach is more useful for lobby organizations in terms of reducing failure and increasing revenue growth. This exception occurs because these organizations must engage a group constrained by a norm prescribing collective agreement. Diverse teams are better positioned to monitor the population as a whole by contacting a broad sample, increasing the validity of identified threats and opportunities. They are in a better position to influence the population of Congress members by recruiting observable champions to their cause who belong to several categories, amplifying the legitimacy of their issue and reducing the appearance of controversy. This mechanism establishes a link between the observed organizational structure and organizational performance.

Keywords: Business.
Advisor: Barnett William A.
Hannan Michael
Rao Hayagreeva
Pore filling and light trapping in solid-state dye-sensitized solar cells [electronic resource]

Dye-sensitized solar cells (DSCs) are among the promising photovoltaic technologies that could potentially replace the expensive silicon. Liquid electrolyte-based DSCs have the highest efficiency but they suffer from potential stability and encapsulation problems when manufactured at high volumes. Research groups are actively pursuing solid state dye-sensitized solar cells (ss-DSCs), which uses a solid-state hole-transport material to replace the liquid electrolyte. SS-DSCs can potentially achieve higher power conversion efficiencies than the liquid-electrolyte because the open-circuit voltage can be adjusted by the choice of different hole-transport materials. However, current ss-DSCs are limited by both pore filling and electron-hole recombination such that the optimal thickness is around 2 microns, far thinner than the thickness needed to achieve good optical absorption. This thesis presents results that address two challenges facing the field of ss-DSC research - what is limiting the thickness of the device, and what can we do to boost light absorption and power conversion efficiency? In the first part, we describe how pore filling of hole-transport materials inside mesoporous TiO2 films is a limiting factor to the device thickness. This is accomplished by three closely-related pore filling projects: (a) quantifying the pore filling of hole-transport materials inside mesoporous TiO2 films; (b) experimenting with new methods to improve pore filling fraction; and (c) investigating the effect of pore filling on photovoltaic performances of ss-DSCs and the underlying photophysical mechanisms. This brings new physical understanding of the importance of pore filling and how pore filling a effects the photovoltaic performances. In the second part, we describe a new device architecture to increase the absorption through the use of plasmonic back reectors, which consist of two-dimensional (2D) array of silver nanodomes. They are incorporated into the ss-DSCs by nanoimprint lithography, and they enhance absorption through excitation of plasmonic modes and increased light scattering.

Keywords: Materials Science and Engineering
Advisor: McGehee Michael
Cui Yi
Sellinger Alan advisor. Thesis advisor