Doping superlattices in conventional and wide-bandgap semiconductors: Physics, properties, and device applications

Doping superlattices (DSLs) provide a multifunctional platform for engineering carrier distribution and band structure in semiconductors. In this work, we present a comprehensive review of the physical mechanisms and device applications of DSLs in both conventional III-V and wide-bandgap semiconductor systems. Based on a self-consistent Schrödinger-Poisson framework within the local density approximation, the formation of subband structures, effective bandgap modulation, and spatial separation of carriers are systematically analyzed. The tunable optoelectronic properties of DSLs are discussed under optical excitation, electrical injection, and external fields, including conductivity, absorption, refractive index, and luminescence. Typical device implementations such as solar cells, photodetectors, electro-optic modulators, and negative-differential-resistance devices are reviewed, with emphasis on the interplay between internal electric fields and carrier recombination dynamics. Furthermore, recent progress in extending DSL concepts to wide-bandgap semiconductors is summarized. In AlGaN, polarization-assisted modulation doping effectively enhances hole activation and transport, while in diamond, \delta -doping and p-i-p-i structures offer a potential route toward high-mobility two-dimensional hole gases. Finally, the feasibility of n-i-n-i superlattice architectures for improving n-type doping in diamond is discussed. These results highlight DSL engineering as a general strategy for tunable and high-performance semiconductor devices.