ALD oxides for GaN interfaces: a comparative view on the flat band

We have deposited a series of ALD oxides HfO ₂ , ZrO ₂ , Ta ₂ O ₅ , Y ₂ O ₃ , SiO ₂ , Al ₂ O ₃ within same reactor and prepared as GaN-MOS structure. A comprehensible diverse distribution of flat-band voltage depending on two different deposition temperatures 100-125°C and 250-300°C, and oxidant H ₂ O or O ₃ was obtained. At zero gate voltage and under unstressed condition we have observed a qualitative feature demonstrating different dependence of the net fixed charge in the oxide or/and at the interface with the deposition temperature, namely, an increase of positive charge for oxidant water oxide and an increase of negative charge for oxidant ozone oxide. Best interface quality, least charge only slightly influenced by the deposition temperature, we have observed for the ZrO ₂ /H ₂ O (oxide/oxidant). Instead, highest deposition temperature dependence we have observed for the Al ₂ O ₃ /H ₂ O.