LAUSR

Abstract III-N surface polarization compensating charge referred here to as ‘surface donors’ (SD) was analyzed in Al 2 O 3 /AlGaN/GaN metal-oxide-semiconductor (MOS) heterojunctions using scaled oxide films grown by metal-organic chemical vapor deposition at 600 °C. We systematically investigated impact of HCl pre-treatment prior to oxide deposition and post-deposition annealing (PDA) at 700 °C. SD density was reduced down to 1.9 × 10 13  cm −2 by skipping HCl pre-treatment step as compared to 3.3 × 10 13  cm −2 for structures with HCl pre-treatment followed by PDA. The nature and origin of SD was then analyzed based on the correlation between electrical, micro-structural, and chemical properties of the Al 2 O 3 /GaN interfaces with different SD density ( N SD ). From the comparison between distributions of interface traps of MOS heterojunction with different N SD , it is demonstrated that SD cannot be attributed to interface trapped charge. Instead, variation in the integrity of the GaO x interlayer confirmed by X-ray photoelectron spectroscopy is well correlated with N SD , indicating SD may be formed by border traps at the Al 2 O 3 /GaO x interface.