Atomic arrangement at the AlN/Si (111) interface

Abstract

High-quality GaN epilayers have been grown on Si (111) substrates by metalorganic vapor phase epitaxy using a low-temperature AlN nucleation layer. The atomic arrangement at the epilayer/substrate interface has been investigated by high-resolution electron microscopy. A crystallographically abrupt interface is observed along most of the epilayer, indicating that the AlN/Si interface is thermodynamically stable and of high crystalline quality. Lattice images at the interface show a periodic array of misfit dislocations. The lattice images have been analyzed in detail in order to obtain information about the atomic arrangement, and interface bonding models are proposed.

Interfacial steps, dislocations, and inversion domain boundaries in the GaN/AlN/Si (0001)/(111) epitaxial system

“…The multiplicity of interfacial structures that has been proposed for the III-N/silicon interface with the (0001)/(111), 〈2110〉/〈110〉 epitaxial orientation relationship [20] necessitates a topological study of possible interfacial structure transformations. A similar analysis has been performed so far only for homophase hcp(0001)/fcc(111) [27].…”

“…In the model interfaces of Fig. 2 we have considered the possibility that either Al or N atoms may comprise the first layer bonded to Si [20]. For analysis of structural transformations between multiple interfacial structures it is helpful to employ bicrystal structure maps or 'cells of non-identical displacements' (cnids) [25].…”

“…6(a). As discussed by Liu et al [20], it is not possible to distinguish on HRTEM micrographs between interfacial structures in which the atoms are single-bonded or triple-bonded between epilayer and substrate. Hence the observed steps could also involve such structure transformations if the substrate steps are not complete steps described by lattice translations but partial steps of height h(µ) = [n + (m/4)] d 111 where n, m are integers.…”

“…24 -26] and an appreciation of their role in the GaN/AlN/Si (0001)/(111) system is required. This particular epitaxial system has recently been assigned a multiplicity of possible interfacial structures and it has been postulated that alternation of distinct interfacial structures is required for charge neutrality [20]. In the present contribution a topological analysis is combined with high-resolution TEM (HRTEM) observations in order to elucidate interfacial structure transformations due to substrate steps and the introduction of IDBs.…”

Magnetron Sputter Epitaxy of High-Quality GaN Nanorods on Functional and Cost-Effective Templates/Substrates

“…Alternatively, Si is an attractive substrate due to its ultra-high crystal quality, low cost, large wafer size (up to 18 inches) availability, and easy integration in integrated circuits industry. However, large mismatches in lattice and thermal expansion coefficients between Si and GaN lead to the formation of poor quality GaN film and generation of cracks, and the high reactivity of atomic nitrogen to Si tends to form an amorphous SiN x layer at the interface [7] that would impede local epitaxial GaN growth and result in growth inhomogeneity [8].…”