Paper
20 December 2004 Surface roughness and dislocation density in InP/InGaAs layers
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Abstract
A subtle roughening of the surface of a buried 60 nm InGaAs epitaxial layer was detected using a combination of sample cleaving, selective chemical etching and Field Emission Scanning Electron Microscopy (FESEM). In our technology, InGaAs is the photo-absorbing layer of Metal Organic Chemical Vapor Deposition (MOCVD) grown layers used in the monolithic integration of active photo detectors and a passive mux/demux. Conventional Photo-Luminescence (PL) and X-Ray Diffraction (XRD) techniques used to monitor and optimize the growth of epitaxial layers did not show this microscopic surface roughness. The appearance of roughness in the InGaAs layer was linked to very large changes in the dislocation density of the layers grown over the rough surface. Increases of up to three orders of magnitude in the Etch Pit Density (EPD from 104 to 107 cm-2) were revealed using a standard Huber Etch. The Huber Etch also showed the preferred formation of "pairs" of dislocations threading out from a common point on the rough InGaAs surface. Changes in growth conditions resulted in the complete elimination of roughness and of excessive dislocation densities
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Denis P. Masson and Sylvain Laframboise "Surface roughness and dislocation density in InP/InGaAs layers", Proc. SPIE 5577, Photonics North 2004: Optical Components and Devices, (20 December 2004); https://doi.org/10.1117/12.567540
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KEYWORDS
Indium gallium arsenide

Etching

Diodes

Surface roughness

PIN photodiodes

Interfaces

Semiconducting wafers

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