Long-Wavelength Photoluminescence from Stacked Layers of High-Quality Type-II GaSb/GaAs Quantum Rings

We report the successful molecular-beam epitaxial growth of 10 stacked layers of GaSb/GaAs quantum rings using a new procedure. Exact control of the arsenic flux during capping helps to reduce the strong group-V As–Sb exchange reactions, enabling the rings to be capped at the same growth temperature (480 °C) without dissolution. X-ray diffraction and transmission electron microscopy indicate excellent structural quality and uniformity with no threading dislocations. This is due to the reduction in the average strain through the quantum-ring formation. The total ring density in the stacks is 1 × 1011 cm–2. An unusually long-wavelength quantum-ring photoluminescence peak of 1.3 μm is observed at low temperature, which is attributed to a reduction in the quantum-ring charging due to lower unintentional p-doping in the GaAs cap layer. The impact that this effect will have on future device designs in solar cells and lasers is also discussed.

[1]  A. Schliwa,et al.  Linking structural and electronic properties of high-purity self-assembled GaSb/GaAs quantum dots , 2012 .

[2]  F. Dinelli,et al.  GaSb quantum dot morphology for different growth temperatures and the dissolution effect of the GaAs capping layer , 2010 .

[3]  T. Ben,et al.  Tuning the properties of exciton complexes in self-assembled GaSb/GaAs quantum rings , 2011 .

[4]  D. Ritchie,et al.  Quantum ring formation and antimony segregation in GaSb∕GaAs nanostructures , 2008 .

[5]  Johannes R. Botha,et al.  Enhanced infrared photo-response from GaSb/GaAs quantum ring solar cells , 2012 .

[6]  P. Galindo,et al.  High resolution electron microscopy of GaAs capped GaSb nanostructures , 2009, Applied Physics Letters.

[7]  Diana L. Huffaker,et al.  Strain compensation technique in self-assembled InAs/GaAs quantum dots for applications to photonic devices , 2009 .

[8]  Diana L. Huffaker,et al.  GaSb∕GaAs type II quantum dot solar cells for enhanced infrared spectral response , 2007 .

[10]  V. A. Solov'ev,et al.  Surface segregation of Sb atoms during molecular-beam epitaxy of InSb quantum dots in an InAs(Sb) matrix , 2007 .

[11]  D. Huffaker,et al.  Formation and optical characteristics of strain-relieved and densely stacked GaSb∕GaAs quantum dots , 2006 .

[12]  Pm Paul Koenraad,et al.  Optical observation of single-carrier charging in type-II quantum ring ensembles , 2012 .

[13]  J. R. Botha,et al.  Type II GaSb/GaAs quantum dot/ring stacks with extended photoresponse for efficient solar cells , 2012 .

[14]  Diana L. Huffaker,et al.  Effect of strain-compensation in stacked 1.3μm InAs∕GaAs quantum dot active regions grown by metalorganic chemical vapor deposition , 2004 .

[15]  Jerry R. Meyer,et al.  Band parameters for III–V compound semiconductors and their alloys , 2001 .

[16]  A. Krier,et al.  Blueshifts of the emission energy in type-II quantum dot and quantum ring nanostructures , 2013 .

[17]  Dieter Bimberg,et al.  450 meV hole localization in GaSb/GaAs quantum dots , 2003 .

[18]  W. S. Lau,et al.  High oxygen and carbon contents in GaAs epilayers grown below a critical substrate temperature by molecular beam epitaxy , 1996 .