With recent trends in miniaturization in the electronics sector, ferroelectrics have gained popularity due to their applications in non-volatile RAM. Taking one step further researchers are now exploring multiferroic devices that overcome the drawbacks of ferroelectric (FE) and ferromagnetic (FM) RAM’s while retaining the advantages of both. The work presented in this dissertation focuses on the growth of FE and FM thin film structures. The primary goals of this work include, (1) optimization of the parameters in the pulsed laser deposition (PLD) of FE and FM films and their heterostructures, (2) development of a structure-property relation that leads to enhancements in electric and magnetic polarizations of these structures, (3) investigation of doping on further enhancement of polarizations and coupling between the FE and FM layers. The materials of choice are La0.7Sr0.3MnO3 (LSMO) as the ferromagnetic and PbZr0.52Ti0.48O3 (PZT) as the ferroelectric component. Epitaxial thin film capacitors were grown using PLD. The work starts with the establishment of the optimum deposition conditions for PZT and goes on to describe results of attempts at performance enhancement and tuning using two methods. It is demonstrated that ferroelectric and ferromagnetic properties can be tuned by inserting a ferromagnetic buffer layer of CoFe2O4 (CFO) between PZT and LSMO. One of the key findings of this work was the anomalously high ferroelectric polarizations produced by lanthanum (La) doped PZT films. This work attempts to shine light on a possible mechanism that leads to such high enhancements in polarization.

MEMS structures utilizing the piezoelectric effect are used to fabricate a wide variation of sensingand actuating devices. The most common piezoelectric material for MEMS is PZT which has beenintensively investigated. In order to improve the performance of PZT and create materialsoptimized for specific applications, altered versions of PZT are being investigated. One way toalter the behavior of PZT is to introduce dopants. In this work, doped and non-doped PZT filmshave been fabricated using the sol-gel deposition process and the transverse piezoelectriccoefficient (e31) value of these films has been measured. Two types of dopants have been used tosee if these dopants could boost the e31 making the film more suitable for energy harvestingapplications. Furthermore processes alteration has been performed to increase the quality andthroughput of the PZT film fabricated at Silex Microsystems. The quality of the film could be seenby inspecting the level of non-uniform areas in regards to color and clarity of the film. The qualitywas improved and the color and clarity uniformity across the wafer was visibly improved. Thethroughput of the PZT deposition process was increased by ~33% by finding an alternative processrequiring fewer crystallization steps. One type of dopant gives an e31 increase of ~12% compared to the highest e31 value previously obtained at Silex Microsystems using non-doped PZT. / Piezoelektrisk MEMS används för att konstruera många olika sorters av sensorer och aktuatorer.Det piezoelektriska material som används mest frekvent inom MEMS är PZT, vilket har blivitintensivt undersökt. För att förbättra prestandan hos PZT och skapa material optimerade förspecifika applikationer, undersöks olika modifikationer av PZT. Ett sätt att modifiera egenskapernahos PZT är att introducera dopningsämnen. I detta arbete har filmer av dopad och odopad PZTtillverkats med en sol-gelprocess och e31-värdet hos dessa filmer har mätts. Två typer avdopningsämnen har använts för att se om ett högre e31-värde kunde nås vilket skulle göra filmenbättre för ”energy harvesting” tillämpningar. Dessutom har process-modifikationer gjorts för attförbättra sol-gel processen hos Silex Microsystems. Modifikationerna gjordes med målet attförbättra kvaliteten hos filmen och minska processtiden. Kvaliteten hos filmen kunde observerasgenom att se i vilken utsträckning filmen var uniform i färg och klarhet. Efter modifikationerna påprocessen så förbättrades både dessa aspekter. Färgskillnader kunde inte längre observeras påfilmen och klarheten ökade. Produktionstiden minskade med ~33% med hjälp av en stabilalternativ process som krävde färre kristalliseringssteg. Ett av dopningsämnena förbättrade e31-värdet med ~12% jämfört med det e31-värdet hos den odopade filmen tidigare skapad av SilexMicrosystems.