Dislocation density reduction via lateral epitaxy in selectively grown GaN structures

Abstract

The microstructure and the lateral epitaxy mechanism of formation of homoepitaxially and selectively grown GaN structures within windows in SiO2 masks have been investigated by transmission electron microscopy (TEM) and scanning electron microscopy. The structures were produced by organometallic vapor phase epitaxy for field emission studies. A GaN layer underlying the SiO2 mask provided the crystallographic template for the initial vertical growth of the GaN hexagonal pyramids or striped pattern. The SiO2 film provided an amorphous stage on which lateral growth of the GaN occurred and possibly very limited compliancy in terms of atomic arrangement during the lateral growth and in the accommodation of the mismatch in the coefficients of thermal expansion during cooling. Observations with TEM show a substantial reduction in the dislocation density in the areas of lateral growth of the GaN deposited on the SiO2 mask. In many of these areas no dislocations were observed.

Overcoming the fundamental light-extraction efficiency limitations of deep ultraviolet light-emitting diodes by utilizing transverse-magnetic-dominant emission

“…Then, 50 nmthick SiO 2 is deposited by plasma-enhanced chemical vapor deposition and selectively opened by photolithographic patterning and wet etching with buffered oxide etchant. The n-GaN microstructures are grown on the opening on the n-AlGaN surface by selective area growth 23,24 by metal-organic vapor phase epitaxy regrowth for 3 min at 1000 6 C at 200 mbar. The V/III ratio is 606, and the silane flow is 50 sccm.…”

High-Efficiency Nitride-Based Solid-State Lighting

“…Although a variety of techniques have been demo nstrated, dislocation reduction has been extensively studied in laterally overgrown c-plane GaN via MOCVD. [8][9][10][11] Low dislocation density substrates obtained through various lateral overgrowth techniques are directly responsible for the remarkable performance of nitride-based optoelectronics, most notably enhanced lifetime cw-InGaN laser diodes. 12 Recently, we have grown planar non-polar a-plane ( 0 2 11 ) GaN films on ( 02 1 1 ) r-plane sapphire substrates via MOCVD.…”

Characterisation of n-type γ-CuCl on Si for UV optoelectronic applications

“…This lattice mismatch is a major factor leading to the generation of misfit dislocations with densities as high as 10 10 cm -2 which can impact on the performance of light emitting devices produced thereupon [1,2]. The introduction of epitaxial lateral overgrowth (ELOG) techniques [3,4] has facilitated the production of III-Nitride films with threading dislocation densities reduced by 3-4 orders of magnitude with respect to conventional metalorganic chemical vapour deposition techniques but it is still very high compared to mature semiconductor technologies. We offer a radically different approach in the field of widebandgap light emitting semiconductors -γ-CuCl on Si.…”