Paper TF+MI+NS-ThA6
Atomic Layer Deposition of HfO₂/Al₂O₃ Nanolaminates on Single-crystal GaN and Ga₂O₃: Investigation of Device Degradation in Power Semiconductor Devices

Thursday, November 2, 2017, 4:00 pm, Room 21

The search for adequate binary metal oxide dielectric nanolaminates (NLs) to prevent degradation of power semiconductor devices is ongoing and involves the atomic layer deposition (ALD)-growth of a variety of binary metal oxide combinations. In the present work, we explore the ALD growth of amorphous (x)HfO₂/(y)Al₂O₃ NLs on Si (with native SiO­₂ layer) substrates and then on both GaN and Ga₂O₃ single crystals. A variety of samples ranging from their homogeneous mixtures to HfO₂ or Al₂O₃-rich NLs are assessed before and after a thermal annealing by spectroscopic ellipsometry (SE), X-ray reflectometry (XRR), X-ray photoelectron spectroscopy (XPS) and 4-point probe resistivity measurements in order to elucidate the structural evolution of the NL at the GaN (or Ga₂O₃)-NL interface. By quantifying the HfO₂ incorporation throughout the Al₂O₃ layer and using the programmable nature of ALD to alternate layers of the HfO₂ and Al₂O₃ in an (AB)_x-(CD)_y fashion, the influence of HfO₂ mobility within Al₂O₃ layer on the NL dielectric constant can be verified unequivocally. Moreover, combined X-ray absorption near-edge (XANES) and X-ray absorption fine structure (XAFS) spectroscopy data obtained at the Advanced Photon Source will confirm the local coordination environment of the Ga at the GaN (or Ga₂O₃)-HfO₂ interface and, at low super-cycle numbers (sub-nm scale), the ultimate stability of the NLs can be probed and optimized such that the bulk material properties are retained.