Influence of Ga(Al)As substrates on surface morphology and critical thickness of InGaAs quantum dots

• Published in: Current applied physics 2019, 19(5), , pp.557-562
• Main Authors: Wang, Yi, Guo, Xiang, Wei, Jiemin, Yang, Chen, Luo, Zijiang, Wang, Jihong, Ding, Zhao
• Format: Article
• Language: English
• Subjects: Al0.25Ga0.75As; Critical thickness; In0.5Ga0.5As; Quantum dots; 물리학
• ISSN: 1567-1739; 1878-1675
• DOI: 10.1016/j.cap.2019.02.010

Influence of Ga(Al)As substrates on surface morphology of InGaAs quantum dots and critical thickness of In0.5Ga0.5As film grown by molecular beam epitaxy is investigated. The In0.5Ga0.5As quantum dots are grown on (001) surfaces of GaAs and Al0.25Ga0.75 A at 450 °C, scanning tunneling microscope images show that the size of quantum dots varied slightly for 10 ML of In0.5Ga0.5As grown on GaAs and Al0.25Ga0.75As surfaces. Reflection high energy electron diffraction (RHEED) is used to monitor the growth of 4 monolayers (ML) In0.5Ga0.5As on Al0.25Ga0.75As and GaAs surfaces during deposition. The critical thickness is theoretically calculated by adding energy caused by surface roughness and heat from substrate. The calculations show that the critical thickness of In0.5Ga0.5As grown on GaAs and Al0.25Ga0.75As are 3.2 ML and 3.8 ML, respectively. The theoretical calculation agrees with the experimental results. •MBE growth of In0.5Ga0.5As quantum dots on GaAs (001) surface and Al0.25Ga0.75As layer at 560°C.•Al0.25Ga0.75As insertion layer is introduced, QD height decrement as well as QD diameter decrease are observed.•Critical thickness calculation was used to explain the QDs morphological changes.•Model of strain was modified to make the calculation for the critical thickness of quantum dots calculation.