UC San Diego

As traditional metal oxide semiconductor field effect transistors (MOSFETs) continue to be scaled to the atomic limit, the need for new materials and new passivation schemes to enable higher performance computing has continued to grow. Atomic layer deposition (ALD) has emerged as a potential solution for both thin film growth as well as materials passivation and because it occurs using surface reactions, the technique can be used in high aspect ratio, 3-dimensional structures commonly found in microelectronic circuits. This dissertation focuses on using variants of the ALD process for both materials passivation as well as materials synthesis.In chapter two, ALD half cycles were used to passivate PbSe nanoparticle solid films. PbSe other lead chalcogenide (PbX, where X = S, Se, or Te) nanoparticles are of increasing interest both in light emitting as well as light harvesting applications due to their tunable optoelectronic properties. Though the materials system holds great promise, progress so far has been limited by the poor carrier transport in these nanoparticle films. Though this poor carrier transport can be due to mesoscale defects in the nanoparticle film, the inherent instability of these materials in ambient conditions also presents a challenge to their continued adoption. Using scanning tunneling microscopy/spectroscopy (STM/STS), it is shown that dosing with half cycles of trimethyl aluminum was able to repair trace oxidation, as evidenced by the elimination of midgap states in STS as well as enhanced transistor performance. In chapters three and four, a variant of ALD known as atomic layer annealing (ALA) was used to deposit crystalline, oriented AlN at low temperature and the mechanism of the ALA process is elucidated using both experimental as well as computational techniques. Crystalline AlN in particular is of interest due to the material properties of high thermal conductivity and high electrical resistivity. These materials can be used to eject heat from high density microelectronic circuits commonly found in logic applications or in high power circuits commonly found in radio frequency circuits. As power dissipation density in these circuits continues to increase, the ejection of heat becomes an increasingly important issue. Using ALA it is shown that high quality, crystalline films can be grown using the technique and by using both experimental techniques as well as molecular dynamics simulations, it is shown that ALA is a momentum transfer process. It is our hope that this better fundamental understanding of the process mechanism will lead to increased adoption of the process for other applications where the deposition of high quality crystalline materials is required.