Abstract

High-quality GaN epitaxial films have been grown on Si substrates with Al buffer layer by the combination of molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) technologies. MBE is used to grow Al buffer layer at first, and then PLD is deployed to grow GaN epitaxial films on the Al buffer layer. The surface morphology, crystalline quality, and interfacial property of as-grown GaN epitaxial films on Si substrates are studied systematically. The as-grown ~300 nm-thick GaN epitaxial films grown at 850 °C with ~30 nm-thick Al buffer layer on Si substrates show high crystalline quality with the full-width at half-maximum (FWHM) for GaN(0002) and GaN(102) X-ray rocking curves of 0.45° and 0.61°, respectively; very flat GaN surface with the root-mean-square surface roughness of 2.5 nm; as well as the sharp and abrupt GaN/AlGaN/Al/Si hetero-interfaces. Furthermore, the corresponding growth mechanism of GaN epitaxial films grown on Si substrates with Al buffer layer by the combination of MBE and PLD is hence studied in depth. This work provides a novel and simple approach for the epitaxial growth of high-quality GaN epitaxial films on Si substrates.

Highlights

  • Due to their unique properties, such as direct band, high thermal stability, etc., GaN and its related III-nitrides have attracted considerable attention for the application in light-emitting diodes (LEDs), especially, liquid crystal display back-lighting, general lighting, and outdoor commercial display[1,2,3]

  • The GaN-based devices prepared on sapphire substrates have already been commercialized[4,5]

  • The direct growth of GaN on Si may lead to the formation of SiGa alloy or/and amorphous SiN during the high temperature growth by metal-organic vapor deposition (MOCVD), for example 1000 °C, which makes hard for the nucleation of GaN epitaxial films and thereby the failure of epitaxy[10,11]

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Summary

Introduction

Due to their unique properties, such as direct band, high thermal stability, etc., GaN and its related III-nitrides have attracted considerable attention for the application in light-emitting diodes (LEDs), especially, liquid crystal display back-lighting, general lighting, and outdoor commercial display[1,2,3]. Due to the large lattice mismatch between buffer layer and Si substrate, high-quality GaN epitaxial films are hard to be obtained.

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