Surface Nanostructuring during Selective Area Epitaxy of Heterostructures with InGaAs QWs in the Ultra-Wide Windows.

Viktor Shamakhov,Nikita Pikhtin,Sergey Slipchenko,Dmitriy Nikolaev,Evgenii Fomin,Ilya Eliseyev,Peter Kop`Ev,Alexander Smirnov

doi:10.3390/nano11010011

Abstract

Selective area epitaxy (SAE) is widely used in photonic integrated circuits, but there is little information on the use of this technique for the growth of heterostructures in ultra-wide windows. Samples of heterostructures with InGaAs quantum wells (QWs) on GaAs (100) substrates with a pattern of alternating stripes (100-μm-wide SiO2 mask/100-μm-wide window) were grown using metalorganic chemical vapour deposition (MOCVD). It was found that due to a local change in the growth rate of InGaAs QW in the window, the photoluminescence (PL) spectra measured from the edge to the center of the window exhibited maximum blueshifts of 14 and 19 meV at temperatures of 80 K and 300 K, respectively. Using atomic force microscopy, we have demonstrated that the surface morphologies of structures grown using standard epitaxy or SAE under identical MOCVD growth conditions correspond to a step flow growth with a step height of ~1.5 ML or a step bunching growth mode, respectively. In the structures grown with the use of SAE, a strong variation in the surface morphology in an ultra-wide window from its center to the edge was revealed, which is explained by a change in the local misorientation of the layer due to a local change in the growth rate over the width of the window.

Highlights

The monolithic integration of electro-optical elements has recently been the subject of extensive research and development in the field of photonic integrated circuits [1,2,3,4,5,6] with various functions including control and generation of both optical and electrical signals.Selective area epitaxy (SAE) [7,8,9] is one of the effective approaches to the implementation of these elements, using selective growth on patterned substrates with passivating masks, which exclude growth above them and ensure growth outside
It is shown that an improvement of radiation characteristics of a quantum wells (QWs) structure obtained using the SAE in the ultra-wide windows requires optimization of the mask pattern parameters, including the narrower width of mask, to ensure minimal variation of the growth rate enhancement (GRE)
This study showed that the GaAs layers grown using the SAE have a morphology different from that of the standard ard epitaxy without a mask (StE) GaAs layers at identical metalorganic chemical vapour deposition (MOCVD) growth conditions

Summary

Introduction

The monolithic integration of electro-optical elements has recently been the subject of extensive research and development in the field of photonic integrated circuits [1,2,3,4,5,6] with various functions including control and generation of both optical (multi-wavelength laser sources, modulators, low-loss waveguides, splitters, combiners, etc.) and electrical signals.Selective area epitaxy (SAE) [7,8,9] is one of the effective approaches to the implementation of these elements, using selective growth on patterned substrates with passivating masks, which exclude growth above them and ensure growth outside (i.e., in the so-called windows). The monolithic integration of electro-optical elements has recently been the subject of extensive research and development in the field of photonic integrated circuits [1,2,3,4,5,6] with various functions including control and generation of both optical (multi-wavelength laser sources, modulators, low-loss waveguides, splitters, combiners, etc.) and electrical signals. Using SAE, one can significantly modify the active region of semiconductor lasers and, fabricate multi-wavelength single-mode laser arrays [17,30], monolithic semiconductor sources of fs laser pulses [31], and tunable semiconductor lasers with an ultra-wide tuning range [15]. The ability of SAE to realize new designs of high-power semilicenses/by/4.0/)

Methods

Results

Conclusion