The importance of overcoming MOVPE surface evolution instabilities for >1.3 $\mu$m metamorphic lasers on GaAs

TL;DR

This paper demonstrates a MOVPE-grown 1.3 μm metamorphic laser on GaAs, overcoming surface instability issues with engineered buffer layers, resulting in efficient, long-wavelength laser emission.

Contribution

It introduces a novel buffer and epitaxial structure to suppress surface instabilities in MOVPE-grown metamorphic lasers, enabling efficient 1.3 μm emission.

Findings

Achieved low lasing threshold and 0.34 W/A slope efficiency.

Extended emission wavelength up to 1360 nm.

Implemented engineered buffer layers to suppress surface defects.

Abstract

We investigated and demonstrated a 1.3 $\mu$m-band laser grown by metalorganic vapour phase epitaxy (MOVPE) on a specially engineered metamorphic parabolic graded In$_x$Ga$_{1-x}$As buffer and epitaxial structure on a GaAs substrate. Bottom and upper cladding layers were built as a combination of AlInGaAs and InGaP alloys in a superlattice sequence. This was implemented to overcome (previously unreported) detrimental surface epitaxial dynamics and instabilities: when single alloys are utilised to achieve thick layers on metamorphic structures, surface instabilities induce defect generation. This has represented a historically limiting factor for metamorphic lasers by MOVPE. We describe a number of alternative strategies to achieve smooth surface morphology to obtain efficient compressively strained In$_{0.4}$Ga$_{0.6}$As quantum wells in the active layer. The resulting lasers exhibited low lasing threshold with total slope efficiency of 0.34 W/A for a 500 $\mu$m long ridge waveguide device. The emission wavelength is extended as far as 1360 nm.