Abstract
The family of III-Nitride semiconductors has been under intensive research for almost 30 years and has revolutionized lighting applications at the dawn of the 21st century. However, besides the developments and applications achieved, nitride alloys continue to fuel the quest for novel materials and applications. We report on the synthesis of a new nitride-based compound by using annealing of AlN heteroepitaxial layers under a Si-atmosphere at temperatures between 1350 °C and 1550 °C. The structure and stoichiometry of this compound are investigated by high resolution transmission electron microscopy (TEM) techniques and energy dispersive X-Ray (EDX) spectroscopy. Results are supported by density functional theory (DFT) calculations. The identified structure is a derivative of the parent wurtzite AlN crystal where the anion sublattice is fully occupied by N atoms and the cation sublattice is the stacking of 2 different planes along <0001>: The first one exhibits a ×3 periodicity along <11–20> with 1/3 of the sites being vacant. The rest of the sites in the cation sublattice are occupied by an equal number of Si and Al atoms. Assuming a semiconducting alloy, a range of stoichiometries is proposed, Al5+αSi5+δN12 with α being between −2/3 and 1/4 and δ between 0 and 3/4.
Highlights
The family of III-Nitride semiconductors has been under intensive research for almost 30 years and has revolutionized lighting applications at the dawn of the 21st century
The surface chemistry of the samples before and after annealing is systematically studied by X-ray photoelectron spectroscopy (XPS)
It should be noted that the ratio of the Al2p peaks after and before annealing is always below 1 indicating a decrease in the Al signal and suggesting that Si atoms have substituted Al ones to form an AlSiN layer
Summary
The family of III-Nitride semiconductors has been under intensive research for almost 30 years and has revolutionized lighting applications at the dawn of the 21st century. A range of stoichiometries is proposed, Al5+αSi5+δN12 with α being between −2/3 and 1/4 and δ between 0 and 3/4 Due to their unique properties, wide-gap group III-Nitrides (III-N) are nowadays the materials of choice for optoelectronic applications especially for light emitting diodes which revolutionized domestic lighting in recent years[1]. The “SiN treatment” is one of the most efficient methods for controling the growth and reducing the threading dislocation density in GaN heteroepitaxial layers, which is mandatory for improving the physical properties of the material up to device quality. The exposure of the GaN surface to a silane/ammonia flux does not lead to the growth of an additional layer but to the replacement of surface Ga atoms by either Si atoms or vacancies Such a SiGaN3 monolayer buried by one monolayer of GaN acts as a dielectric mask and prohibits further GaN growth. The red arrows in (a) indicate the first planes showing the characteristic contrast of AlSiN
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