Properties of Thin Film-Covered GaN(0001) Surfaces

In-K-edge x-ray absorption fine structure (EXAFS), x-ray photoelectron, and Raman spectroscopy results are combined for a comprehensive study of InxGa1−xN layers with energy gaps extending over nearly the whole visible spectrum. The In–N and In–(In,Ga) distances determined by EXAFS are used for the derivation of the In–N bond ionicity as well as for the phonon frequency dependence of the LO and B12 modes, assessed by Raman, and the N 1s, In 3d5/2, Ga 3s, and Ga 2p1/2 electron binding energies on those distances. Phonon confinement due to perturbation of the periodic potential caused by the alloying is also quantified.

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Investigation of atomic layer deposition methods of Al2O3 on n-GaN

Tadmor,

Vandenbroucke,

Bahat Treidel

et al. 2024

Journal of Applied Physics

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In this work, three atomic layer deposition (ALD) approaches are used to deposit an Al2O3 gate insulator on n-GaN for application in vertical GaN power switches: thermal ALD (ThALD), plasma-enhanced ALD (PEALD), and their stacked combination. The latter is a novel method to yield the most ideal insulating layer. Also, the influence of an in situ NH3 or H2 plasma pre-treatment is studied. Planar MIS capacitors are used to investigate the electrical properties and robustness of the gate insulators. In vacuo x-ray photoelectron spectroscopy (XPS) is used to study the changes in chemical composition after every surface treatment. XPS shows that all plasma pre-treatments efficiently remove all carbon contamination from the surface, but only NH3 plasma is observed to additionally remove the native oxide from the n-GaN surface. The water precursor step in the ThALD process does not completely remove the CH3 ligands of the trimethylaluminum precursor step, which might electrically be associated with a reduced forward bias robustness. The O2 plasma step in the PEALD process is associated with the removal of carbon and a tremendous increase of the O content in the GaN surface region. Electrically, this strongly correlates to an enhanced forward bias robustness and an increased forward bias hysteresis, respectively. The ThALD/PEALD stack method mitigates the shortcomings of both ALD processes while maintaining its advantages. Electrical measurements indicate that the stack method alongside NH3 plasma pretreatment provides the best characteristics in terms of hysteresis, threshold voltage, forward bias robustness, and interface trap density of states.

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Properties of Thin Film-Covered GaN(0001) Surfaces

Cited by 3 publications

References 107 publications

GaN thin film: Growth and Characterizations by Magnetron Sputtering

GaN thin film: Growth and Characterizations by Magnetron Sputtering

Scaling of phonon frequencies and electron binding energies with interatomic distances in InxGa1−xN

Investigation of atomic layer deposition methods of Al2O3 on n-GaN

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