Thin films are utilized in various applications, including LEDs, solar cells, and microelectronics. Technological advancements necessitate the development of increasingly thinner materials. Researchers in this field face the challenges of developing advanced materials. One approach to address this is by devising new process strategies that enable the synthesis of new materials. This thesis explores the conformal chemical vapor deposition of boron carbide thin films, highlighting the various strategies developed to achieve conformal thin film depositions on intricate morphologies. These materials find applications in solid-state neutron detectors as a neutron converter layer, in the encapsulation of carbon nanotubes, and as free-standing tubular material grown on carbon nanotubes.

Triethyl boron (TEB, B(C₂H5)₃) was used as a single source precursor, with its hydrocarbon ligand serving as the carbon source. By limiting the reaction kinetics, excellent conformality with a B-rich composition of B_5.2C was achieved in 10:1 aspect ratio structure at 450 °C. The process was further explored with complex morphologies and various temperature regimes, adopting further strategies for the desired characteristics. The kinetically limited growth regime is a compromise between achieving good film conformality at a lower temperature and obtaining higher density at higher temperature. Competitive co-diffusion as a new strategy with the prospect of improving the step coverage at higher temperatures for better film properties was experimented. Using a heavy inert gas (Xe) as a diffusion additive enabled conformal deposition at 550 °C by enhancing the step coverage from 0.71 to 0.97 in 10:1 aspect ratio feature. This process was further tested to encapsulate random oriented carbon nanotubes (CNT) within a membrane structure, achieving uniform deposition B4C thin films without clogging pore sites and allowing tunable porosity. The compatibility observed for B₄C thin film growth on CNT surface was achieved without causing significant stress or structural damage, but with a near-surface epitaxial templating. Building on the approach of diffusion additive, adding Kr to the ALD process for AlN resulted in a superconformal deposition in 18:1 aspect ratio Si microstructures.

The uniformity of film depositions on CNT membrane began to decline with an increased roughness at deposition temperatures above 700 °C. This was mainly due to the flux limited CVD regime, which typically results in sub-conformal growth on intricate morphologies. Although B₄C deposition on CNT at 550 °C exhibited a near-surface epitaxial templating, this was not maintained towards the exterior of the cylindrical composite structure. This challenge is analogous to trying to match two dissimilar geometries, i.e., packing rhombohedral unit cell structures on a radial surface. On the other hand, boron carbide can transform into graphitic phase by adding more C. Graphitic layers will be flexible to wrap-around the cylindrical structure of CNTs by adding extra walls to it. By operating in the thermodynamically limited regime, the process uniquely favored the graphitic phase formation and a tubular growth fashion on CNTs. Tubular graphitic boron carbide (g-BC_x) growth on both single-walled and few-walled CNTs are demonstrated. The process appears to be a viable route for synthesizing B-doped graphitic nanomaterials, which hold promises for the next generation electronics applications.