Polarity tuning of crystalline AlN films utilizing trace oxygen involved sputtering and post-high-temperature annealing

The polarity tuning of AlN films via introducing a period of trace oxygen supply in the initial sputtering process was demonstrated. High-temperature annealing was further implemented to improve the crystal quality of AlN. High-quality pure N-polar AlN film could be achieved by sputtering with pure N₂ gas. When trace oxygen was intentionally inputted in the sputtering chamber and its supply time surpassed 150 s, the AlN surface polarity transmitted to pure Al-polar. After optimization, the full widths at half of maximum of X-ray rocking curves for (0002)/(10-12) reflection were improved to 41.3/132.5 arcsec for N-polarity and 38.2/158.7 arcsec for Al-polarity. (author)