Recently, there has been renewed interest in wide and ultra-wide semiconductors as materials for energy and electronics. Batteries, fuel cells or solar cells, among other energy production and storage devices, can be improved by the introduction of WBG. For these applications, WBG can add new aspects in ultra-efficient anodes, nanocomposites, or as extraction layers for electrons and holes, among many other applications.

For power electronics, WBG such as silicon carbide (SiC), gallium nitride (GaN), or gallium oxide (Ga2O3) allow power electronic components to be smaller, faster, more reliable, and more efficient than their silicon (Si)-based counterparts. There is a large range of opportunities that are being opened up by the mainstream adoption of wide bandgap semiconductors for power electronics, making it possible to reduce weight, volume, and life-cycle costs in a wide range of power applications, resulting in dramatic energy savings in industrial processing and consumer appliances, the accelerated widespread use of electric vehicles and fuel cells, and helping to integrate renewable energy onto the electric grid.

Some frontier semiconductors such as AlGaO and AlGaN are now perhaps among the most promising material systems to extend the WBG beyond 5eV in the emerging field of ultra-wide bandgap semiconductors. This area of research is growing fast, as we are pushing the limits of semiconductors with wider bandgaps, critical electric fields, and power figure of merits.

In addition, some WBG materials can be engineered to be transparent, flexible, or biocompatible, which will certainly pave the way for new electronic and energy avenues—in particular, transparent conducting oxides for optoelectronics where new amorphous WBG oxides are revolutionizing the field. Another vibrant related field of research are deep UV optoelectronics, where wide and ultra-wide bandgap materials promise to extend the current range of deep UV photodiodes, detectors, and also LEDs well below the visible range.

The present Special Issue is devised as a collection of articles, reporting both concise reviews of recently obtained results and new findings produced in this broad research area.

Dr. Amador Pérez Tomás
Dr. Ekaterine Chikoidze
Prof. Dr. Mike Jennings
Guest Editors