The origins and elimination of oval defects in GaAs layers grown by molecular beam epitaxy

Abstract

Oval defects in GaAs layers are serious impediments to GaAs device fabrication. Of particular importance is the relationship between the droplets deposited on the crucible walls and the number of oval defects. These droplets previously believed to be gallium oxides are shown to consist of GaAs shells covering the Ga particles. By increasing the wall temperature of the crucible orifice, and reducing the arsenic beam intensity, the density of droplets is reduced, thus decreasing oval defects. Using a uniform-heated Ga effusion cell and adjusting the cell configuration, the droplets can be reduced substantially and the defect density can be reduced from >104 cm−2 to less than 200 cm−2.

Optimization of MBE-grown GaSb buffer layers and surface effects of antimony stabilization flux

“…The deposition technology of choice for such heterostructures, in particular those with quantum wells or superlattices, is typically molecular beam epitaxy (MBE) due to the high layer thickness precision (single monolayer) and ability to form abrupt interfaces. While high quality growth techniques and appropriate equipment considerations have been shown to reduce the surface defect density of MBE-grown GaAs to only few per square centimeter [2,3], defect densities in GaSb remain comparatively high.…”

High power mid-wave and long-wave infrared light emitting diodes

“…Often the most accommodating substrate for growth of 6.1Å heterostructures is GaSb due to availability and the ease of lattice-matching. While MBE growth of arsenide compounds has been honed to the point that only few oval defects per square centimeter are obtainable [61,62], growth of GaSb is comparatively immature and defect densities are generally much higher. Suppression of surface roughness and defects (both microstructural and oval) is necessary to produce high quality optoelectronic devices with high yield across the wafer and good device consistency.…”