Influence of GaAs Substrate Orientation on InAs Quantum Dots: Surface Morphology, Critical Thickness, and Optical Properties

Bl Liang,Zh M Wang,Ka Sablon,Yu I Mazur,Gj Salamo

doi:10.1007/s11671-007-9103-3

Bl Liang, Zh M Wang + Show 3 more

Open Access

https://doi.org/10.1007/s11671-007-9103-3

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Abstract

InAs/GaAs heterostructures have been simultaneously grown by molecular beam epitaxy on GaAs (100), GaAs (100) with a 2° misorientation angle towards [01−1], and GaAs (n11)B (n = 9, 7, 5) substrates. While the substrate misorientation angle increased from 0° to 15.8°, a clear evolution from quantum dots to quantum well was evident by the surface morphology, the photoluminescence, and the time-resolved photoluminescence, respectively. This evolution revealed an increased critical thickness and a delayed formation of InAs quantum dots as the surface orientation departed from GaAs (100), which was explained by the thermal-equilibrium model due to the less efficient of strain relaxation on misoriented substrate surfaces.

Highlights

Self-assembled InGaAs/GaAs semiconductor quantum dots (QDs) attracted extensive research efforts due to their unique properties as ‘‘artificial atoms’’ [1–3]
The sample grown on (911)B surface could be regarded as an example, which has a low density of small QDs with weak PL emission and a strong wetting layer (WL) signal with a life time between the typical quantum well (QW) and WL of InAs QDs
As the substrate misorientation angle increased from 0° to 15.8°, our results indicated a delayed formation of InAs QDs, which means an increased critical thickness

Summary

Introduction

Self-assembled InGaAs/GaAs semiconductor quantum dots (QDs) attracted extensive research efforts due to their unique properties as ‘‘artificial atoms’’ [1–3]. Understanding and controlling the growth of InGaAs/GaAs QDs were important both for fundamental studies and in view of their potential in optoelectronic device applications In this arena, it is well known that the GaAs substrate orientation has a large impact on the formation and properties of the. Henini’s group developed the thermalequilibrium model [18] and theoretically proved that the critical thickness of forming InAs QDs on high index surfaces increased as the substrate orientation departed from the GaAs (100) [19]. This proof was reinforced experimentally on GaAs (511)B surface (substrate misorientation of 15.8°) and GaAs (311)B surface (substrate misorientation of 25.2°) [19, 20]. From the atomic force microscope (AFM) characterization and photoluminescence (PL) investigation, a clear evolution from QDs to quantum well (QW) was observed while the substrate misorientation angle increased from 0° to 15.8°

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