Felix Rolf Lutz Lange

Interband characterization and electronic transport control of nanoscaled GeTe / Sb 2 Te 3 superlattices

The extraordinary electronic and optical properties of the crystal-to-amorphous transition in phase-change materials have led to important developments in memory applications. A promising outlook is offered by nanoscaling such phase-change structures. Following this research line, we study the interband optical transmission spectra of nanoscaled

Development of an adaptive laser beam shaper

\text{GeTe}/{\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}

Impact of vacancy ordering on thermal transport in crystalline phase-change materials.

chalcogenide superlattice films. We determine, for films with varying stacking sequence and growth methods, the density and scattering time of the free carriers, and the characteristics of the valence-to-conduction transition. It is found that the free carrier density decreases with increasing GeTe content, for sublayer thicknesses below

(GeTe)x–(Sb2Te3)1–x phase‐change thin films as potential thermoelectric materials

\ensuremath{\sim}3

Disorder-Induced Localization in Crystalline Pseudo-Binary

nm. A simple band model analysis suggests that GeTe and

GeTe-Sb_{2}Te_{3}

{\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}

Alloys between

layers mix, forming a standard GeSbTe alloy buffer layer. We show that it is possible to control the electronic transport properties of the films by properly choosing the deposition layer thickness, and we derive a model for arbitrary film stacks.

Ge_{3}Sb_{2}Te_{6}

The intensity distribution of a laser beam has a high impact on laser processing applications. In many applications, the emitted light of a laser beam source is transformed from a Gaussian intensity distribution into other intensity distributions with the intent to improve the process quality. Numerous approaches have been pursued for this purpose in the past. The vast majority of these optical systems is static. As a result the laser material processing process is limited to a specific intensity distribution. Different systems like membrane deformable mirrors can be used for shaping multiple intensity distributions. However, the control of such systems is complex and requires a deep understanding of the underlying operating principle of the specific mirror system. In this paper a new approach for active beam shapers made of catalog components, like spherical and cylindrical lenses, is introduced. Two optical systems for active beam shaping are designed which can change between two different intensity distributions by moving an individual spherical/ cylindrical lens along the beam path. One system forms a laser spot with Gaussian like intensity distribution and a TopHat shaped intensity distribution respectively. The second optical system is capable of forming a laser spot with Gaussian intensity distribution and a homogenous line shaped intensity distribution respectively. Also the mechanical housing for these optical systems is presented.