Comparison of MOVPE grown GaAs, InGaAs and GaAsSb covering layers for different InAs/GaAs quantum dot applications

• Published in: Journal of crystal growth Vol. 464; pp. 59 - 63
• Main Authors: Zíková, Markéta, Hospodková, Alice, Pangrác, Jiří, Oswald, Jiří, Hulicius, Eduard
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.04.2017; Elsevier BV
• Subjects: A3. MOVPE; A3. Quantum dot; A3. Strain reducing layer; B2. GaAsSb; B2. InAs; B2. InGaAs; Flat layers; Gallium arsenide; Heterostructures; Indium arsenides; Indium gallium arsenides; Metalorganic chemical vapor deposition; Photoluminescence; Quantum dots; Simulation; Strain; B2. InAs; A3. Strain reducing layer; B2. InGaAs; A3. Quantum dot; B2. GaAsSb; A3. MOVPE
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2016.11.110

InAs/GaAs quantum dot (QD) heterostructures with different covering layers (CLs) prepared by MOVPE are compared in this work. The recombination energy of a structure covered only by GaAs depends nonlinearly on CL thickness. Experimental data of photoluminescence (PL) were supported by theoretical simulations. These simulations prove that the strain plays a major role in the structures. InGaAs strain reducing layer (SRL) was studied as well. Due to the strain reduction, the recombination energy is decreased, so the structure has longer PL wavelength. By theoretical simulations it was shown that for high content of In in InGaAs covering layer (approximately 45% and more), the heterostructure is type II, which would normally be unreachable for flat layers. For the structure with GaAsSb SRL, the band alignment is highly dependent on the SRL composition. The type I/type II transition occurs for approximately 15% of Sb; this value also slightly depends on the QD size. All structures were also studied by HRTEM to show different behavior of the CLs on the interface with InAs which highly influences the structure quality. •Advantages and disadvantages of InGaAs and GaAsSb QD SRL are identified.•The most effective thickness of strain reducing layer is suggested.•Type II band alignment for QDs with InGaAs SRL is predicted for the first time.•GaAsSb SRL with different composition for various applications is introduced.