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This chapter investigates Dutch pamphlet coverage of the 1655 massacre of the Waldensians. Comparing textual and visual representations of the violence, the chapter argues that persecuted minorities and their advocates stepped into a complex communicative landscape when they sought publicity for foreign suffering. Close investigation of this landscape will offer insights into how early modern consumers of print media were invited to feel concern about the plight of faraway strangers.

In the early modern period, images of revolts and violence became increasingly important tools to legitimize or contest political structures. This volume offers the first in-depth analysis of how early modern people produced and consumed violent imagery, and assesses its role in memory practices, political mobilization, and the negotiation of cruelty and justice.

In this letter, we explore in detail the potential of nanoheteroepitaxy to controllably fabricate high quality GeSn nano-structures and to further improve the crystallinity of GeSn alloys directly grown on Si(001). The GeSn was grown by molecular beam epitaxy at relatively high temperatures up to 750 degrees C on pre-patterned Si nano-pillars embedded in a SiO2 matrix. The best compromise between selective GeSn growth and homogenous Sn incorporation of 1.4% was achieved at a growth temperature of 600 degrees C. X-ray diffraction measurements confirmed that our growth approach results in both fully relaxed GeSn nano-islands and negligible Si interdiffusion into the core of the nanostructures. Detailed transmission electron microscopy characterizations show that only the small GeSn/Si interface area reveals defects, such as stacking faults. Importantly, the main part of the GeSn islands is defect-free and of high crystalline quality. The latter was further demonstrated by photoluminescence measurements where a clear redshift of the direct CC-CV transition was observed with increasing Sn content.

In this work we present an innovative approach to realise coherent, highly-mismatched 3-dimensional heterostructures on substrates patterned at the micrometre-scale. The approach is based on the out-of-equilibrium deposition of SiGe alloys graded at an exceptionally shallow grading rate (GR) of 1.5% µm −1 by low energy plasma enhanced chemical vapour deposition (LEPECVD). Fully coherent SiGe/Si crystals up to 6 µm in width were achieved as confirmed by defect etching and transmission electron microscopy (TEM) analyses. The experimental results are supported by calculations of the energy for dislocation formation which indicate that elastic relaxation is energetically favoured over plastic relaxation in the narrower heterostructures. X-ray diffraction measurements show that the SiGe crystals are strain-free irrespective of the stress relieving mechanism which changes from elastic to plastic by increasing their width. The impact of dislocations on the SiGe crystal quality is analysed by comparing the width of X-ray diffraction peaks as a function of the heterostructure size.

L'integrazione monolitica di funzionalità fotoniche nella micro-tecnologia basata su silicio è un obiettivo ampiamente perseguito dalla comunità scientifica, con applicazioni nella comunicazione di dati e nella rilevazione nel vicino e medio infrarosso. L’integrazione di componenti attivi e passivi con processi di fabbricazione standard è già avanzata. Tuttavia, ancora non esiste una soluzione per una sorgente di radiazione efficace attivata elettricamente. Un grande sforzo di ricerca si concentra sulle eterostrutture di germanio (Ge) e silicio (Si). Tuttavia, il Ge è un semiconduttore a gap indiretto con efficienza quantica scarsa rispetto ai materiali a gap diretta. Un’alta deformazione e un pesante drogaggio sono stati proposti come metodi per migliorare la densità di portatori nella valle della banda di conduzione diretta del Ge e sono generalmente accettati come una strategia valida per raggiungere un guadagno ottico positivo negli strati di Ge. In questa tesi proponiamo un approccio top-down per la realizzazione di stressori nanostrutturati di SiGe, basati sulla differenza di passo reticolare tra SiGe e Ge. Per mezzo di spettroscopia micro-Raman dimostriamo che il Ge localmente viene deformato uniassialmente fino al 4%. Per limitare la diffusione degli elettroni eccitati dalle regioni altamente deformate, viene studiato sistematicamente l'inserimento di una barriera di SiGe sotto uno strato superficiale di Ge. I risultati dimostrano che durante la termalizzazione gli elettroni superano la barriera di diffusione. Per aumentare il volume deformato e utilizzare il vuoto come barriera, gli stressori di SiGe sono stati trasferiti su un sottile ponte di Ge. Confrontando lo strain ottenuto per il ponte e il bulk, i valori assoluti di strain sono nell'ordine di 0,7%. Tuttavia, la deformazione relativa indotta da nanostrutture nel micro-ponte è 1,3% a causa della alta condivisione di energia elastica tra nanostrutture e ponte. Quindi, la realizzazione di nanostrutture su ponti raddoppia il valore di deformazione rispetto alle stesse nanostrutture su bulk. Questo potrebbe consentire, a parità di deformazione, di avere una più grande zona deformata. Inoltre, abbiamo studiato la fotoluminescenza da Ge drogato fosforo, selettivamente cresciuto in finestre di SiO2 su un substrato di Si, in funzione delle condizioni di crescita. I parametri di crescita comprendono la temperatura di deposizione, il flusso di drogante e i trattamenti termici. La variazione del flusso di drogante ha mostrato che il drogaggio aumenta l'intensità di PL fino a una concentrazione ottimale. Per spiegare la dinamica della ricombinazione abbiamo utilizzato a una serie di campioni con concentrazioni differenti. Misure di PL a diverse temperature e potenze di eccitazione sono state confrontate con un modello teorico. Per la simulazione degli spettri di PL e’ stato utilizzato un modello numerico autoconsistente a multi-valle e massa efficace, che considera l'impatto dei droganti sulle dinamiche di ricombinazione non-radiativa. In questo modello proponiamo una dipendenza lineare del tasso di ricombinazione relativo a difetti in funzione della densità del donatore. Quindi il meccanismo di Shockley-Read-Hall (SRH) domina il canale di ricombinazione non-radiativa fino a una densità di donori pari a 5 × 10^19 cm-3. L’aumento e la successiva diminuzione dell'intensità di PL in funzione del doping potrebbero essere spiegati da un calo di due ordini di grandezza della densità di portatori in eccesso, causato da una diminuzione del tempo di vita legato alla ricombinazione SRH non radiativa. Il raggiungimento di una deformazione elevata e un alto drogaggio in strati di Ge, nonché una comprensione delle dinamiche di ricombinazione, sono di grande interesse per la prospettiva di realizzare un laser basato su Ge. The monolithic integration of photonic functionality into silicon micro-technology is a widely-sought goal with projected applications in data-communication and sensing for the near- and mid-infrared spectral range. The realization of integrated passive and active components with means of standard silicon manufacturing processes is already widely advanced. Yet there is no final solution for an effective, electrically pumped light source. A lot of research effort focuses on germanium (Ge) on silicon (Si) hetero-structures. However, Ge is an indirect gap semiconductor with scarce quantum efficiency as compared to intrinsic direct gap materials. High tensile strain and heavy n-type doping have been proposed to enhance the carrier density in the Ge direct conduction band valley and are accepted as a route to achieve positive optical gain in Ge layers. We propose a top-down fabrication for external stressors made of SiGe nanostructures that is based on the lattice mismatch of SiGe and Ge. By means of micro-Raman spectroscopy we demonstrate that Ge is locally deformed and a uniaxial tensile strain of up to 4 % is reached. However, the photo-luminescence from the strained volume is scarce and the emission spectra are bulk like. To constrain the excited electrons to the highly strained regions, the insertion of a SiGe barrier below a shallow layer of Ge is investigated systematically showing that during thermalization carriers overcome the barrier by diffusion. To enlarge the strained volume and to have vacuum as the barrier, we transfer the SiGe stressors to a thin Ge micro-bridge and compare the obtained strain to the case of an attached bulk-like Ge layer. Absolute strain values are of the order of ~ 0.7 % for both micro-bridge and bulk. However, the relative strain induced by the nanostructures in the micro-bridge is 1.3 % due to the high sharing of elastic energy between nanostructures and bridge. Hence, the suspension doubles the strain value with respect to a bulk like system which could conversely allow a larger strained area in the suspended material at constant strain. Moreover, we investigate the photoluminescence from phosphorous doped Ge selectively grown in SiO2 windows on a Si substrate in dependence of the growth conditions. Investigated growth parameters comprise deposition temperature, in-situ dopant flux and postbake condition. The variation of the dopant flux (phosphine PH3 pressure) during in-situ doping at Ge deposition temperatures Tdep = 350 °C and 400 °C revealed that doping increases the PL intensity up to an optimum doping concentration resulting in maximum PL. To elucidate the recombination dynamics in n-doped germanium we revert to a series of phosphorous doped Ge with different dopant concentrations. PL measurements at different temperatures and excitation powers are then compared with theoretical modeling. A self-consistent multi-valley effective mass numerical model for simulation of PL spectra is employed that considers the impact of dopants on the non-radiative recombination dynamics in which we propose a linear dependence of the defect-related recombination rate as a function of the donor density. We find that the Shockley-Read-Hall (SRH) mechanism dominates the non-radiative recombination channel up to a donor density of ~ 5 ×1019 cm-3. The observed increase and successive decrease of PL intensity as a function of doping could be accounted for by a drop of two orders of magnitude in the excess carrier density that is caused by a reduction of the non-radiative Shockley-Read-Hall lifetime. Our model proposes a lifetime reduction from ~ 30 ns in the intrinsic case to ~ 0.1 ns for doping in the 1019 cm-3 range. The achievement of controlled high strain values and heavy doping in Ge layers as well as a proper understanding of the recombination dynamics are of high interest with the prospect to achieve a Ge-based laser.

Photoluminescence (PL) of selectively grown phosphorus (P) doped germanium (Ge) is investigated. 350–600 nm thick P-doped Ge is grown on 100 nm thick P-doped Ge buffer layer, which is annealed at 800 °C before the main part of Ge deposition. In the case of Ge deposited at 325 °C, approximately two times higher PL intensity is observed by P doping of ~3.2×1019 cm−3. Further increase of PL intensity by a factor of 1.5 is observed by increasing the growth temperature from 325 °C to 400 °C due to improved crystal quality. Varying PH3 partial pressure at 400 °C, red shift of the PL occurred with increasing P concentration due to higher bandgap narrowing. With increasing P concentration up to ~1.4×1019 cm−3 at 400 °C the PL peak intensity increases by filling electrons into the L valley and decreases due to enhanced point defect concentration and degraded crystallinity. By post-annealing at 500–800 °C, the PL intensity is further increased by a factor of 2.5 because of increased active P concentration and improved crystal quality. Reduced direct bandgap energy by introducing tensile strain is also observed.

The introduction of strain in semiconductors is a well-known technique exploited in microelectronics to increase their mobility and thus to enhance the performance of silicon-based electronic devices. Moreover, tensile strain is one feasible route towards converting Ge into an efficient light emitter. Here we show how the application of local strain via nanopatterning opens a wider parameter space for strain engineering in semiconductors of the Si/Ge material system. The general approach relies on the top-down fabrication of SiGe stressors realized by electron-beam lithography (EBL) and reactive-ion etching (RIE). Specifically, compressive strain can be locally applied to pure Si and tensile strain can be applied to pure Ge. Raman spectroscopy is used to investigate the strain induced in Si or Ge bulk like substrates. Furthermore, the realization of stressors on micro-bridges demonstrates higher achievable strain level if compared to the attached bulk-like case. The strain enhancement is due to the high sharing of elastic energy in between the nanostructures and the bridges. The SiGe stressor approach hence presents a CMOS compatible alternative for strain creation in Si, Ge and SiGe.

The monolithic integration of photonic functionality into silicon microtechnology is widely advanced. Yet, there is no final solution for the realization of a light source compatible with the prevailing complementary metal-oxide-semiconductor technology. A lot of research effort focuses on germanium (Ge) on silicon (Si) heterostructures and tensile strain application to Ge is accepted as one feasible route to make Ge an efficient light emitter. Prior work has documented the special suitability of Ge membranes to reach the high tensile strain. We present a top-down approach for the creation of SiGe stressors on Ge micro-bridges and compare the obtained strain to the case of an attached bulk-like Ge layer. We could show that the Ge influenced by a SiGe stressor is under tensile strain; absolute strain values are of the order of 0.7% for both micro-bridge and bulk. The relative strain induced by the nanostructures in the micro-bridge is 1.3% due to the high sharing of elastic energy between nanostructures and bridges.

Integration of photonics and electronics still lacks a light source that is monolithically integrable into existing CMOS technology. Germanium is investigated as a promising candidate for the active gain medium for a laser source, since it is CMOS compatible and because of its quasi-direct band-structure. Tensile strain in Ge decreases the energy barrier between the indirect and direct conduction band valleys to facilitate carrier injection into the direct gap in Γ. We propose a top-down method to strain Ge on Si layers by nano-structured SiGe layers. The method consists of the coherent growth of SiGe on Ge. The tensile SiGe top-layer can relax when trenches are carved, thereby pulling apart the Ge in between. FEM strain simulations show that the effect of SiGe nanostructures can be stronger if their perimetral forces are exerted on a Ge membrane rather than on bulk. The enhancement of elastic energy transfer from nanostructure to the membranes can result in the fabrication of larger strained regions of Ge. We present our first µRaman results for SiGe stressors on 100 nm thick Ge suspended membranes. While the strain is still below the induction of a direct-gap transition, we can show that SiGe nanostructures fabricated on a membrane are about twice as effective in creating strain as compared to the same nanostructures created on bulk Ge.

An experiment has demonstrated that truly dislocation free SiGe crystals with widths of at least 5μm can be epitaxially grown on Si substrates by applying the compositional grading developed for layers to 3D structures. At such crystal widths, the epitaxial growth of SiGe alloys with a constant high Ge content inevitably leads to the injection of dislocations. The reason is that at dimension far above the nanoscale the low aspect ratio of the SiGe/Si system during the initial stages of the growth does not allow for sufficient elastic strain relaxation. The findings suggest that there is no limit to the final Ge content, and that the grading rate can be suitably tailored in order to give access to even larger dislocation-free structures. Indeed, preliminary experimental results indicate similar absence of dislocations in SiGe crystals graded to a fi nal Ge content of 80%. Combining this method with layer transfer techniques makes it possible to form dislocation-free SiGe patches many micrometers in size acting as virtual substrates with lattice parameters intermediate to those of Si and Ge on an Si substrate.

We show that a relatively simple top-down fabrication can be used to locally deform germanium in order to achieve uniaxial tensile strain of up to 4%. Such high strain values are theoretically predicted to transform germanium from an indirect to a direct gap semiconductor. These values of strain were obtained by control of the perimetral forces exerted by epitaxial SiGe nanostructures acting as stressors. These highly strained regions can be used to control the band structure of silicon-integrated germanium epilayers. (C) 2015 AIP Publishing LLC.