Showing papers by "Adam William Saxler published in 1994"
TL;DR: In this article, a model between AlN thin films and sapphire substrates was proposed to explain the process of crystal growth, and extended atomic distance mismatch was used to interpret the results.
Abstract: High‐quality thin aluminum nitride films were grown on different orientations of sapphire substrates by metalorganic chemical vapor deposition. (00⋅1) AlN thin film grown on (00⋅1) Al2O3 has better crystallinity than (11⋅0) AlN on (01⋅2) sapphire. Full width at half maximum of a rocking curve is 97.2 arcsec, which is the narrowest value to our knowledge. A crystallographic model between AlN thin films and sapphire substrates was proposed to explain the process of crystal growth. ‘‘Extended atomic distance mismatch’’ which is the mismatch of atomic distance for a longer period was introduced. It is shown that the mismatch is relaxed by edge‐type dislocations. Extended atomic distance mismatch was used to interpret the results that (00⋅1) AlN has better crystallinity than (11⋅0) AlN, but (11⋅0) GaN has better crystallinity than (00⋅1) GaN.
98 citations
TL;DR: In this article, the growth of high quality AlN epitaxial layers on sapphire substrates was reported, and the AlN peak on (01⋅2) Al2O3 was about 30 times wider.
Abstract: In this letter we report the growth of high quality AlN epitaxial layers on sapphire substrates. The AlN grown on (00⋅1) sapphire exhibited a better crystalline quality than that grown on (01⋅2) sapphire. An x‐ray rocking curve of AlN on (00⋅1) Al2O3 yielded a full width at half‐maximum of 97.2 arcsec, which is the narrowest value reported to our knowledge. The AlN peak on (01⋅2) Al2O3 was about 30 times wider. The absorption edge measured by ultraviolet transmission spectroscopy for AlN grown on (00⋅1) Al2O3 was about 197 nm.
96 citations
TL;DR: In this article, the epitaxial growth of wurtzite-type thin films such as gallium nitride (GaN) on different orientations of sapphire (Al2O3) substrates is described.
Abstract: In this article, we present a crystallographic model to describe the epitaxial growth of wurtzite‐type thin films such as gallium nitride (GaN) on different orientations of sapphire (Al2O3) substrates. Through this model, we demonstrate the thin films grown on (00⋅1)Al2O3 have a better epilayer‐substrate interface quality than those grown on (01⋅2)Al2O3. We also show the epilayer grown on (00⋅1)Al2O3 are gallium‐terminated, and both (00⋅1) and (01⋅2) surfaces of sapphire crystals are oxygen‐terminated.
88 citations
TL;DR: In this article, the relationship between the thermal stability of GaN films and the substrate's surface polarity was studied and it appeared that the N−terminated (0001) GaN surface was the most stable surface.
Abstract: Single crystals of GaN were grown on (0001), (0112) Al2O3 and (0001)Si 6H‐SiC substrates using an atmospheric pressure metalorganic chemical‐vapor‐deposition reactor. The relationship has been studied between the thermal stability of the GaN films and the substrate’s surface polarity. It appeared that the N‐terminated (0001) GaN surface grown on (0001)Si 6H‐SiC has the most stable surface, followed by the nonpolar (1120) GaN surface grown on (0112) Al2O3, while the Ga‐terminated (0001) GaN surface grown on (0001) Al2O3 has the least stable surface. This is explained with the difference in the atomic configuration of each of these surfaces which induces a difference in their thermal decomposition.
83 citations