Final answer:
In CVD diamond synthesis, a lower temperature leads to a greater diamond thickness primarily because it reduces the rate of etching or removal of diamond from the substrate. It can also influence crystal size and quality, although the complete process involves several factors that need to be optimized.
The correct answer is options D) Lower temperatures reduce the rate of etching or removal of diamond from the substrate.
Step-by-step explanation:
For CVD (Chemical Vapor Deposition) diamond synthesis, the temperature within the reaction chamber plays a significant role in determining the characteristics of the diamond produced. In this context, a lower temperature is often associated with a greater height value or thickness of the CVD diamond.
This effect can be attributed mainly to the reduced rate of etching or removal of diamond from the substrate at lower temperatures. While higher temperatures increase reaction rates and promote faster growth, they also accelerate the etching processes which counteract growth. Thus, when the temperature is lowered, the reduced etching rate results in a net increase in diamond thickness.
Moreover, lower temperatures may affect surface mobility and the quality of the diamond being grown. These temperatures may support the formation of larger, well-faceted crystals as opposed to the smaller, more numerous crystals favored by higher temperatures. Nonetheless, it is important to note that this is a multifaceted process and that the efficient removal of by-products and the concentration of diamond precursors in the gas phase are also influential factors that require optimization.
The correct answer is options D) Lower temperatures reduce the rate of etching or removal of diamond from the substrate.