Herbert S. Mączko

• Ph.D. in Physics
• Physicist at nextnano GmbH

The pseudomorphic growth of Ge1-xSnxon Ge causes in-plane compressive strain, which degrades the superior properties of the Ge1-xSnx alloys. Therefore, efficient strain engineering is required. In this article, we present strain and band-gap engineering in Ge1-xSnxalloys grown on Ge a virtual substrate using post-growth nanosecond pulsed laser melt...

Band gap alignments of BGaInAs/GaAs quantum wells with mole fractions of indium around 40% and mole fractions of boron ranging from 0% up to 4.75% are studied experimentally by photoreflectance (PR) and photoluminescence (PL). Obtained results are explained within a k · p model within an envelope function approximation. The study shows an increase...

In this paper, we derive a ready-to-use symmetry-invariant expansion of the full-zone 30-band k·p Hamiltonian for the Td point group. To find respective parameters, the band structures of III-V materials were calculated within a state-of-the-art density functional theory (DFT) approach and used next as targets to adjust the k·p bands. A satisfactor...

In this work we derive a ready-to-use symmetry invariant expansion of the full-zone 30-band k.p Hamiltonian for the Td point group. In order to find respective parameters, the band structures of III-V materials were calculated within a state-of-the-art Density Functional Theory (DFT) approach and used next as targets to adjust the k.p bands. A sati...

First principles calculations are increasingly often used in device modelling. However, due to their complexity and high computational costs, simplified but reliable models are of great value. In this work, we present an original method of finding the 30-band k·p parameters on an example of Ge1-xSnx alloy. It allows to reproduce the electronic band...

21st-century studies in the field of epitaxy brought observable progress in a field of heterogeneous integration of III-V materials onto silicon photonic systems. BGaAs/GaP quantum wells (QWs) are a new material system, which can be grown on GaP/Si templates and thereby can be integrated with a Si platform. This work presents calculations of the ma...

Light emitters integrated with Si platform are highly desirable for photonic integrated circuits, however, manufacturing them remains difficult. In this work, BGaAs/GaP quantum well (QW) structures are proposed as a promising solution of the challenge. These QWs can be grown on GaP/Si templates, which are intensively developed for recent years. An...

Abstract 8-band k · p Hamiltonian together with envelope function approximation and planewave expansion method are applied to calculate the electronic band structure and material gain for Ge1−wSnw/SiyGe1−x−ySnx/Ge1−wSnw quantum wells (QWs) grown on virtual Ge1-zSnz substrates integrated with Si platform. It is clearly shown how both the emission wa...

In this work band structure and optical gain was calculated for Ge/Ge1-xSnx/Ge quantum wells. Ottomanization of x composition and the thickness of the well d were made for use in semiconductor lasers. As a result of optimization achieved the optimum parameter values of quantum wells: 0.15 < x < 0.17, d ~ 12 nm. © 2017, Wydawnictwo SIGMA - N O T Sp....

It is shown that compressively strained Ge1-xSnx/Ge quantum wells (QWs) grown on a Ge substrate with 0.1 ≤ x ≤ 0.2 and width of 8 nm ≤ d ≤ 14 nm are a very promising gain medium for lasers integrated with an Si platform. Such QWs are type-I QWs with a direct bandgap and positive transverse electric mode of material gain, i.e. the modal gain. The el...

Unstrained Ge 1−xSnx layers of various Sn concentration (1.5%, 3%, 6% Sn) and Ge 0.97Sn0.03 layers with built-in compressive (ε = −0.5%) and tensile (ε = 0.3%) strain are grown by molecular beam epitaxy and studied by electromodulation spectroscopy (i.e., contactless electroreflectance and photoreflectance (PR)). In order to obtain unstrained GeSn...