III-nitrides have the potential to address a large number of fundamental needs for semiconductor device applications, including full-spectrum/tandem-with-silicon solar cells (InGaN), RGB LEDs (InGaN), UV LEDs and lasers (AlGaN), and high-power diodes and transistors (AlGaN). However, many of these applications remain unrealized due to challenges in growing high-quality material by traditional growth techniques like metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). Through control of growth kinetics, metal-modulated epitaxy (MME) has been shown to have success in growing III-nitrides, especially highly doped films and ternary alloys with compositions in the miscibility gaps unreachable by other techniques. This control of growth kinetics is expected to lead to the realization of devices that have driven interest in this material system but have thus far been unachievable. This dissertation focuses on progressing the understanding of material synthesis and properties at the extreme ends of the III-nitride material range, with a particular emphasis on InGaN, AlGaN, and AlN.