Electron-spin-resonance studies of AlGaN/GaN MIS-HEMT structures with Al2O3 fabricated by atomic layer deposition

We performed electron-spin-resonance (ESR) investigations of defects related to dangling bonds (DBs) around the insulator/semiconductor interface in Al2O3/AlGaN/GaN MIS-HEMT structures on Si. The Al2O3 layer was fabricated by atomic layer deposition, and we studied the effects of the Al2O3 layer thickness and the post-deposition annealing (PDA) temperature on the number of DBs (N-db). The N-db of the AlGaN/GaN HEMT structure was reduced by deposition of the 10-nm-thick Al2O3 layer. The N-db value at the 5-nm-thick Al2O3/AlGaN interface decreased to a minimum value with PDA at 500 degrees C. We show that defects related to DBs around ALD-Al2O3/AlGaN interfaces can be reduced by optimizing the ALD-Al2O3 thickness and PDA temperature.