Epitaxial growth of quantum dots on InP for device applications operating at the 1.55 μm wavelength range

The development of epitaxial technology for the fabrication of quantum dot (QD) gain material operating in the 1.55 μm wavelength range is a key requirement for the evolvement of telecommunication. High performance QD material demonstrated on GaAs only covers the wavelength region 1-1.35 μm. In order to extract the QD benefits for the longer telecommunication wavelength range the technology of QD fabrication should be developed for InP based materials. In our work, we take advantage of both QD fabrication methods Stranski-Krastanow (SK) and selective area growth (SAG) employing block copolymer lithography. Due to the lower lattice mismatch of InAs/InP compared to InAs/GaAs, InP based QDs have a larger diameter and are shallower compared to GaAs based dots. This shape causes low carrier localization and small energy level separation which leads to a high threshold current, high temperature dependence, and low laser quantum efficiency. Here, we demonstrate that with tailored growth conditions, which suppress surface migration of adatoms during the SK QD formation, much smaller base diameter (13.6nm versus 23nm) and an improved aspect ratio are achieved. In order to gain advantage of non-strain dependent QD formation, we have developed SAG, for which the growth occurs only in the nano-openings of a mask covering the wafer surface. In this case, a wide range of QD composition can be chosen. This method yields high purity material and provides significant freedom for reducing the aspect ratio of QDs with the possibility to approach an ideal QD shape.

[1]  T. Jones,et al.  Surface morphology evolution during the overgrowth of large InAs–GaAs quantum dots , 2001 .

[2]  M. Seul,et al.  Domain Shapes and Patterns: The Phenomenology of Modulated Phases , 1995, Science.

[3]  K. Yvind,et al.  Low-jitter and high-power 40-GHz all-active mode-locked lasers , 2004, IEEE Photonics Technology Letters.

[4]  Matthias Kuntz,et al.  High-Speed Mode-Locked Quantum-Dot Lasers and Optical Amplifiers , 2007, Proceedings of the IEEE.

[5]  Philippe Caroff,et al.  High-gain and low-threshold InAs quantum-dot lasers on InP , 2005 .

[6]  Kresten Yvind,et al.  Low-noise monolithic mode-locked semiconductor lasers through low-dimensional structures , 2008, SPIE OPTO.

[7]  Peter Blood,et al.  Characterization of semiconductor laser gain media by the segmented contact method , 2003 .

[8]  M. Thompson,et al.  InGaAs Quantum-Dot Mode-Locked Laser Diodes , 2009, IEEE Journal of Selected Topics in Quantum Electronics.

[9]  Andrea Fiore,et al.  Simultaneous two-state lasing in quantum-dot lasers , 2003 .

[10]  Kresten Yvind,et al.  Investigating the chemical and morphological evolution of GaAs capped InAs/InP quantum dots emitting at 1.5μm using aberration-corrected scanning transmission electron microscopy , 2011 .

[11]  E. Rafailov,et al.  Mode-locked quantum-dot lasers , 2007 .

[12]  Elias Towe,et al.  Self-assembled (In,Ga)As/GaAs quantum-dot nanostructures: strain distribution and electronic structure , 2002 .

[13]  Kresten Yvind,et al.  Metal organic vapor-phase epitaxy of InAs/InGaAsP quantum dots for laser applications at 1.5 μm , 2011 .

[14]  Morten Willatzen,et al.  Computational Methods for Electromechanical Fields in Self-Assembled Quantum Dots , 2012 .

[15]  G. E. Pikus,et al.  Symmetry and strain-induced effects in semiconductors , 1974 .

[16]  Luke J. Mawst,et al.  Nanofabrication of III–V semiconductors employing diblock copolymer lithography , 2010 .

[17]  Xinyu Li,et al.  Thermodynamic theory of shape evolution induced by Si capping in Ge quantum dot self-assembly , 2009 .

[18]  K. Kern,et al.  Interplay between thermodynamics and kinetics in the capping of InAs/GaAs(001) quantum dots. , 2006, Physical review letters.

[19]  L. Voon,et al.  The k p Method: Electronic Properties of Semiconductors , 2009 .

[20]  Y Yohan Barbarin,et al.  Stacking, polarization control, and lasing of wavelength tunable (1.55 μm region) InAs/InGaAsP/InP (100) quantum dots , 2007 .

[21]  Mitsuru Sugawara,et al.  Quantum-dot semiconductor optical amplifiers , 2002, SPIE/OSA/IEEE Asia Communications and Photonics.

[22]  D. Poitras,et al.  An L-band monolithic InAs/InP quantum dot mode-locked laser with femtosecond pulses. , 2009, Optics express.

[23]  Jeong-Yong Choi,et al.  Large area tunable arrays of graphene nanodots fabricated using diblock copolymer micelles , 2012, Nanotechnology.

[24]  Lei Zhang,et al.  Optical gain and absorption of quantum dots measured using an alternative segmented contact method , 2006, IEEE Journal of Quantum Electronics.

[25]  G. Fredrickson,et al.  Block Copolymers—Designer Soft Materials , 1999 .

[26]  L. J. Mawst,et al.  Quantum dot active regions based on diblock copolymer nanopatterning and selective MOCVD growth , 2011, IEEE Winter Topicals 2011.