Influence of HfO2 and SiO2 interfacial layers on the characteristics of n-GaN/HfSiOx capacitors using plasma-enhanced atomic layer deposition

We investigated the growth per cycle (GPC) for SiO2 and HfO2 on n-GaN/native oxide and p-Si/SiO2 substrates by plasma-enhanced atomic layer deposition using tris(dimethylamino)silane and tetrakis(dimethylamino)hafnium precursors, respectively, and O-2 plasma gases. On the basis of the estimated GPC, we also examined the characteristics of n-GaN/Hf0.57Si0.43Ox/Pt capacitors with an inserted interfacial layer (IL) such as subnanometer-thick HfO2 and SiO2. We found that the GPC for SiO2 on n-GaN/native oxide was slightly smaller than that on p-Si/SiO2, whereas the GPC for HfO2 was the same on both substrates. The GPC for ALD-SiO2 could be reasonably plotted on the basis of the relationship between the GPC and the difference in electronegativity between the metal and oxygen in the metal-O underlayers including native oxide (Ga2O3) on GaN. On the basis of the GPC on n-GaN, Hf0.57Si0.43Ox (23 nm) capacitors were fabricated without and with a HfO2-IL (0.3 and 0.5 nm) or SiO2-IL (0.3 and 0.6 nm). These capacitors exhibited similar leakage current properties and a high breakdown electric field greater than 8.3 MV cm(-1). No frequency dispersion and a flatband voltage (V-fb) hysteresis smaller than 50 mV were observed for all of the capacitors. Compared with the SiO2-IL [Si-rich HfSiOx (Si: > 0.43)] capacitors, the HfO2-IL [Hf-rich HfSiOx (Hf: > 0.57)] capacitors showed a smaller interface state density [(1.2-1.7) x 10(11) cm(-2) eV(-1) at -0.4 eV from the conduction band] and a smaller negative V-fb shift. Therefore, the Hf-rich HfSiOx (Hf: > 0.57) grown using a HfO2-IL at the n-GaN/HfSiOx interface plays a substantial role in improving the electrical properties of n-GaN/HfSiOx capacitors.

Automated summary

The study explores the growth per cycle (GPC) of SiO2 and HfO2 on different substrates, and the characteristics of capacitors with inserted interface layers. Results suggest that Hf-rich HfSiOx plays a significant role in improving the electrical properties of capacitors.