Threading dislocations in epitaxial InN thin films grown on (0001) sapphire with a GaN buffer layer

Abstract

The density and types of threading dislocations (TDs) in InN thin films grown on (0001) sapphire with a GaN buffer layer were characterized by transmission electron microscopy. Perfect edge TDs with 13〈112̄0〉 Burgers vectors are predominant defects which penetrate the GaN and InN layers. Pure screw and mixed TDs were also observed. Overall the TD density decreases during film growth due to annihilation and fusion. The TD density in GaN is as high as ≈1.5×1011 cm−2, and it drops rapidly to ≈2.2×1010 cm−2 in InN films. Most half-loops in GaN are connected with misfit dislocation segments at the InN/GaN interface and formed loops, while some TD segments threaded the interface. Half-loops were also generated during the initial stages of InN growth.

Effect of charged dislocation scattering on electrical and electrothermal transport inn-type InN

“…Because InN growth is exclusively heteroepitaxial, usually on GaN, threading dislocation (TD) densities in InN are very high, typically in the range of 10 9 − 10 11 cm −2 . [15][16][17] It is clear at least qualitatively that dislocations play a role in limiting electron transport in n-type InN. For example, studies of non-radiative recombination 18 and of electron transport (mobility) 14,19,20 have found deleterious effects which are attributed to charged dislocations.…”

Optimization of the surface and structural quality of N-face InN grown by molecular beam epitaxy

“…6,7 Indeed, a few experimental studies of undoped InN point to room temperature electron mobilities exceeding 2000 cm 2 /V s. 8,9 For the In-face orientation, numerous attempts, using mainly plasma-assisted molecular beam epitaxy ͑MBE͒, have been undertaken to generate good crystal and surface quality for improved optical and transport properties. The implementation of various buffer layers, such as AlN, 10 lowtemperature InN, 11 and GaN, 9,12 has helped especially to reduce free electron carrier concentration and sharpen the optical absorption edge, partly overcoming the lack of a near-lattice-matched substrate. However, the low InN decomposition temperature presents significant growth challenges, limiting the growth temperature to Ϸ500°C.…”

Origin of the n-type conductivity of InN: The role of positively charged dislocations

“…11 This variation is due to the annihilation and fusion of the dislocations with increasing growth. 12 To account for the charge associated with the dislocations, a term has been added to Eq. ͑2͒, such that…”