A novel approach to increase emission wavelength of InAs/GaAs quantum dots by using a quaternary capping layer

Abstract

In this paper, we present a new approach to obtain large size dots in an MBE grown InAs/GaAs multilayer quantum dot system. This is achieved by adding an InAlGaAs quaternary capping layer in addition to a high growth temperature (590°C) GaAs capping layer with the view to tune the emission wavelength of these QDs towards the 1.3 μm/0.95 eV region important for communication devices. Strain driven migration of In atoms from InAlGaAs alloy to the InAs QDs effectively increases the size of QDs. Microscopic investigations were carried out to study the dot size and morphology in the different layers of the grown samples. Methods to reduce structural defects like threading dislocations in multilayer quantum dot samples are also studied.

Strain relaxation in InAs quantum dots through capping layer variation and its impact on the ultrafast carrier dynamics

“…Among various SRLs, InAlGaAs has been a strong candidate for growing high quality QDs with higher aspect ratio and minimum size dispersion [12]. Previously, many researchers have adopted different techniques and methods to increases the efficiency with InAlGaAs SRL in the QD heterostructures by optimizing the (i) growth rate, (ii) capping layer thickness, (iii) material composition, (iv) InAs monolayer coverage [13][14][15][16][17]. Although, the structural properties of such QD heterostructures are well documented in the earlier reports, the proper correlation in between the structural, optical properties and carrier dynamics is hardly reported in the literatures which is very much important in the improvement of fabricating modern age optoelectronic devices such as infrared photodetector and intermediate band solar cell.…”