Investigation of AlN thin film growth on MgO(111) substrates using low temperature helicon sputtering system

• Epitaxial AlN films were obtained on the as-received and annealed MgO(111).
• The crystalline quality of AlN films was improved on annealed MgO(111).
• Two different growths were found for the deposition of AlN on annealed MgO.
• Growth mechanism of AlN on MgO(111) using sputtering is investigated.
• Dislocations of AlN films can be reduced on substrates with small lattice mismatch.

An aluminum nitride (AlN) thin film has been grown on annealed magnesium oxide (MgO) (111)-plane substrate using low temperature helicon sputtering system. Both AlN films on as-received and annealed MgO(111) substrate are single crystalline with AlN[0001] || MgO[111]. X-ray rocking curve shows that AlN film on annealed MgO exhibits superior crystalline quality, which means more suitable for AlN crystal growth. Two different growths were found for the deposition of AlN on annealed MgO. It is believed that the partially recovered substrate surface caused by annealing process provides atomic smooth surface terraces with small lattice mismatch for AlN crystal to grow in 2D mode, enhance grain size, and thus reduce the dislocation density. This is the first time demonstrated for the growth mechanism of single crystal AlN thin film prepared on MgO(111) by sputtering system.