Plasma immersion ion implantation (PIII) is an established technique in certain niche microelectronics applications such as the synthesis of silicon-on-insulator. In other applications such as shallow junction formation by plasma doping, trench doping, and fabrication of blue light emitting materials, PIII has unique advantages over conventional techniques and may be the technique of choice in the future. There have been significant developments in these areas and recent breakthroughs in plasma and trench doping are discussed in this review paper. Results pertaining to direct-current PIII that excels in planar sample processing as well as the optical characteristics of nano-cavities produced by hydrogen PIII are also presented.