Low-temperature plasma-enhanced ALD of c-axis textured GaN on sapphire

Abstract

This paper demonstrates the deposition of GaN on c-plane sapphire by plasma-enhanced atomic layer deposition (PE-ALD) at 250 °C using triethylgallium and forming gas (95% N2, 5% H2) plasma. The films exhibit a wurtzite crystal structure with a full-width at half maximum of 0.31° for the (0002) peak via x-ray diffraction and an abrupt GaN–sapphire interface confirmed by scanning transmission electron microscopy. X-ray photoelectron spectroscopy and secondary-ion mass spectrometry reveal carbon and oxygen concentrations of 1 at. % and less than 3 at. %, respectively. Transfer length method analysis demonstrates a sheet resistance of 1.37 × 108Ω/□. These results provide an understanding for the low-temperature PE-ALD growth of GaN with high crystalline fidelity and minimized impurity incorporation.