What is it about?

We demonstrated that high-quality lightly-doped (~10^16 cm^-3) n-type Gallium nitride (GaN) layer growth via cost-effective halogen-free vapor phase epitaxy (HF-VPE), which employs the simplest reaction to grow GaN. We obtained a carbon-free (< 5 x 10^13 cm^-3, electron mobility collapse causative impurity) lightly n-type GaN layer, and other O, B, Fe, Mg, Al, Ca, Cr, Zn, Ni, Mn, and Ti impurity contents were below the detection limits of secondary ion mass spectrometry. Furthermore, we identified the Ca impurity as a deep acceptor in GaN, another killer defect leading to mobility collapse.

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Why is it important?

To realize vertical-type GaN power devices with low on-resistance and kV-class breakdown voltage for automobile applications, we should explore the cost-effective and high-quality growth method (such as carbon impurity reduction for preventing electron mobility collapse) for a lightly-doped n-type drift layer. Furthermore, to avoid increasing the on-resistance of GaN power devices, we should clarify the other causative impurities of the mobility collapse.


We hope our experimental demonstration will accelerate the realization of the vertical-type GaN power device applications.

Taishi Kimura
Toyota Central R&D Labs., Inc.

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This page is a summary of: Impurity reduction in lightly doped n-type gallium nitride layer grown via halogen-free vapor-phase epitaxy, Applied Physics Letters, January 2024, American Institute of Physics,
DOI: 10.1063/5.0191774.
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