Indium content impact on structural and optical properties of (In,Ga)As/GaP quantum dots
Abstract
Despsite many efforts undertaken by the semiconductor scientific community, the demonstration of room-temperature laser source electrically pumped monolithically grown on silicon substrate is still an important challenge [1]. Amongst III-V semiconductors, GaP appears as a promising candidate thanks to its small lattice mismatch with Si [2]. Nevertheless, devices based on GaP materials need to deal with the difficulty to obtain efficient active area due to its indirect character. To overcome this, (In,Ga)As quantum dots (QDs) [3] were proposed. In this contribution, Influence of indium content on structural and optical properties is investigated in order to promote the direct optical transition of QDs. Four nominal In content: 10, 25, 35 and 50% of (In,Ga)As/GaP QDs grown by solid source molecular beam epitaxy (SS-MBE) on GaP substrate are analyzed by photoluminesence and atomic force microscopy (AFM) experiments. Significant redshift is reported in comparison between QDs with 10% to 35% of In content due to the valence band modification [4]. Moreover, it is shown that, while for low In contents a monomodal QDs distribution is observed [Fig1.a], a bimodal one appears for In contents reaching 35% and beyond [Fig1.b]. Controlling this distribution is a great challenge for obtaining a direct bandgap emission with GaP-based materials.
This research project is supported by the Labex Cominlabs project: "3D Optical Many Cores" and the OPTOSI ANR project N°12-BS03-002-02.
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