Earth‐abundant, fluorescent silicon carbide (SiC) quantum dots (QDs) have recently attracted remarkable attention on account of their long‐term chemical and optical stability and impressive biocompatibility. However, there has been a long‐standing debate among researchers concerning whether radiative recombination in SiC QDs is governed by quantum confinement effects or by surface‐related states. Herein, the underlying mechanism responsible for the photoluminescence observed in SiC QDs is elucidated. Significant progress made through the development of advanced strategies for synthesizing ultrasmall SiC QDs and modifying their surfaces with functional groups, conjugated molecules, and protective shells is discussed. Subsequently, the potential for engineered SiC QDs to be applied to a range of sectors, including energy (photocatalytic‐based CO₂ reduction systems), electronics/optoelectronics (electroluminescent white light‐emitting diodes, nonlinear optics, and quantum sensing), and biomedicine (cell imaging and biosensors), is reviewed. Finally, this review is summarized with some forward‐looking challenges and prospects.

Electroluminescence of porous silicon carbide is achieved in a forward-biased SiC p–i–n junction. A broad green spectral feature centered at ∼510 nm is shown to arise from porous SiC. A large SiC surface area in the vicinity of the junction is created by diamond cutting followed by an electrochemically enhanced hydrogen fluoride etch that produces a layer of porous SiC. Photoluminescence is shown not to be responsible for the green emission. This supports the model of carrier recombination at the porous region via lateral bipolar diffusion of carriers. A lateral bipolar diffusion model is presented in which mobile carriers diffuse laterally from the junction toward the porous SiC surface region driven by a lateral carrier concentration gradient. Lateral bipolar diffusion in conjunction with suitable radiative recombination centers provides a possible pathway to achieve high quantum efficiencies in future SiC p–n homojunction or double heterojunction light-emitting diodes. Competing recombination processes and associated ideality factors in 4H-SiC diodes are also examined.

The influence of microindentation on the electroluminescence of silicon carbide was studied in forward-biased 4H SiC p-i-n junctions. Four spectral regions at approximately 390, 420, 445 and 500 nm initially observed on virgin samples strongly depend, in regard to magnitude, on the condition of the starting die. These spectral regions may be interpreted as arising from either phonon-assisted band-to-band transitions or from defect-related transitions. The same SiC die were then subjected to mechanical damage brought about by a series of closely spaced microindentations directed approximately perpendicular to the c-axis. The spectra taken after a first set and subsequently a second set of microindentations are distinct from the initial spectra in all cases, and differences are interpreted as being due to the modification of existing defects or additional defects being generated mechanically. The influence of microindentation on the ideality factor is measured and discussed. Measured light flux with respect to a standard light source is also shown at each microindentation stage.

Stacking faults in silicon carbide have been widely studied due to their negative impact on the application of silicon carbide in the power electronics industry. In this work, with the assistance of forward biasing, we observe several triangular shaped structures emerging near the indenter imprint in two separate 4H–SiC bipolar junction transistor samples that were deformed by nanoindentation. Based on the study of electroluminescence spectra on one of the samples, the emission peak at 420 nm indicates the formation of single Shockley stacking faults inside deformed transistors. We conclude that the use of indentation can provide a method to study recombination induced stacking faults in silicon carbide junction devices by intentionally introducing dislocations at selected areas of interest.

Fluorescent silicon carbide quantum dots have recently attracted attention due to their long-term chemical and optical stability, non-toxicity, biocompatibility, and ultra-low cost. More highly developed III-V and II-V quantum dots lack this combination of positive attributes. We review recent progress in the synthesis protocols and applications of silicon carbide quantum dots together with their resulting optical properties that aim to overcome the well-known indirect bandgap exhibited by all known silicon carbide polytypes. These advancements are accomplished by new approaches to preparing ultrasmall quantum dots that achieve quantum confinement. In addition, surface modifications may be realized by a rapidly growing range of functional groups, conjugated molecules, and shells. Recent advancements in the modeling of fluorescent nanoscale quantum dots using density functional theory are enabling unprecedented insights into fluorescence mechanistics. The application of engineered silicon carbide quantum dots to a range of problems is reviewed. Key target sectors include energy, electronics, optoelectronics, biomedical cell imaging and biosensors.

Temperature-dependent variation in the intensity of 390 nm phonon-assisted, band-to-band radiative recombination in 4H-SiC is measured from −156 to 86.5 °C. Our data show a consistent rise in electroluminescence intensity with increasing temperature in a SiC p–n junction. Derivation of an appropriate model, based on single, dominant electron–phonon coupling and Bose–Einstein phonon occupancy statistics, is shown to fit well with our experimental data. We observe a single phonon–electron coupling, and we directly obtain a phonon frequency of 20.4 THz, which is within experimental error of literature optical phonon frequencies in SiC. We use curve fitting to obtain values of the required unknown constants for the first time without resorting to any adjustable parameters. The direct proportionality between the rate of radiative recombination and the absorption coefficient is reaffirmed. Further application of our modelling is presented using literature data for 4H-SiC electroluminescence extending up to 526.85 °C. We further identify phonon overtones and/or phonon combination modes that may participate in assisting with the band-to-band radiative recombination in indirect bandgap semiconductors. We make available our curve-fitting app to researchers for their ease of use.