Comparative energetics of nanovoid growth in wide- and ultrawide-band gap semiconductors

The emergence of wide- and ultra-wide-bandgap semiconductors has helped expand the field of power devices. The wide band gaps enable these materials to handle large applied voltages, but their reliability in radiation-rich environments is still under investigation. In this project, we examine the comparative energetics of void growth, nucleated at either pre-existing vacancies or vacancies generated by ion beams, in SiC, GaN, AlN, AlGaN alloys, and β–Ga₂O₃. We employ density functional theory to calculate the energies to sequentially remove atoms neighboring the initial cation or anion vacancy to distant interstitial sites. Low atom-removal energies, the order of the material’s band gap, suggest that the material would be vulnerable to nanovoid growth, with the necessary energy provided either by the high voltages, Joule heating, recombination of excess electron-hole pairs, or combinations thereof. The potential roles of nanovoid formation in the degradation and failure of electronic devices will be discussed.