Characterization of switching capabilities and the process of fabrication of memory elements on TaS2

Že nekaj časa smo v iskanju novih računalniških tehnologij, ki bi nam omogočile nadaljnje izboljšave na tem področju. Eden od glavnih sestavnih delov je tudi spomin, ki je v zadnjih letih doživel precej napredka, predvsem na podlagi novih tehnologij. Primer tega je tudi spominski element, ki je obravnavan v tem delu. Glavni del elementa je material TaS2, v katerem se vzpostavi t. i. val gostote naboja oz. CDW (ang. charge density wave). Sistem doživi fazni prehod in dvig električne upornosti za več kot dekado. Vrednost upornosti je mogoče upravljati s pomočjo električnih pulzov. Za preklop v stanje nizke upornosti se uporabi kratek pulz nizke napetosti. Temu prehodu pravimo zapis oz. "write". Pri izbrisu oz. "erase" se poslužimo gretja materiala, ki se povrne v osnovno stanje. To izvedemo z daljšim pulzom nizke napetosti, upornost se spremeni z nizke nazaj na visoko vrednost. Magistrska naloga predstavi teoretično ozadje materiala TaS2, CDW pojava ter zapisa in izbrisa. Nato je na vrsti eksperimentalni del, v katerem prikaže sintezo materiala, načrtovanje in izdelavo testnega vezja ter končni produkt. Sledijo meritve in rezultati, s katerimi pokažemo preklopne lastnosti in stabilnost elementa, ter prikaz izdelave večbitnega prototipa. Na koncu so zbrane še končne ugotovitve in primerjava z ostalimi vrstami spomina.We have been in search of new technologies that would allow for the development in computer science for quite some time. One of the main building blocks is the computer memory, which has seen a lot of progress in the recent years, mainly due to the new memory technologies. A memory element which is the subject of this thesis is also one of them. The main part of the element is the material called TaS2, which undergoes a phase transition from the ground state to the so called charge density wave state or CDW. Electrical resistance rises for more then ten times when that happens and can be manipulated using an electrical pulse. To achieve a transition from high to low resistance one has to apply a short pulse of low voltage, we call that writing. In order to erase back to the state of high resistance, a longer pulse of small amplitude has to be used. This thesis shows the theoretical background of the TaS2, the CDW transition and the write and erase phenomena. It\u27s followed by the experiment, which consists of material synthesis, planning and fabrication of the memory element and the final product. It then presents the measurements and results, which demonstrate the attributes of our device. There is also an illustration of how a multi bit device would look like. At the end there are some final conclusions and a few comparisons amongst other memory devices