Film Memory Research Articles

(Digital Presentation) Temporal Evolution of the Threshold Voltage in Organic Thin Film Memory Transistors

We present a procedure to monitor the temporal evolution of the trapped charge in floating gates of organic thin film transistors (OTFTs) based memories in dynamic regimes. The potential applications of organic semiconductors in flexible and wearable electronics and their known features such as low-temperature and solution fabrication make the OTFTs be considered as candidates also in the field of non-volatile memories. Past efforts have been devoted on the preparation and optimization of floating gates [1]. In the present work, we focus on the modelling of this kind of devices, in particular, on a model for the threshold voltage useful in dynamic experiments, such as hysteresis and transient regimes. The information extracted from the modelling and simulation of these devices can be related to technological parameters with the objective of finding a better memory design.Current-voltage curves impacted by hysteresis are usually reproduced assuming the threshold voltage to be constant or piecewise constant. Nevertheless, despite positive outcomes [2], this is not a precise approach since it does not consider the actual temporal evolution of the threshold voltage. Thus, a time dependent threshold voltage is mandatory in order to interpret hysteresis phenomena and transient experiments, which in turn can be associated to trapping and de-trapping mechanisms over time.In this work, a model that describes the evolution of the threshold voltage with the time, which is linked to the variation of the trapped charge in the channel, is proposed.The evolution of the trapped charge is described with a first-order linear differential equation with a term controlled by a time constant t, and another term, similar to the generation term in a typical continuity equation, which is proportional to the drain current flowing through the transistor channel. This model is introduced in a compact model previously developed for OTFTs that include contact effects [3–6]. The resulting model is combined with an evolutionary parameter extraction procedure, which is applied to experimental current–voltage curves taken from the literature that show both contact and hysteresis effects [7]. Figures (a) and (b) show the best fitting of our calculations (solid lines) and experimental output and transfer characteristics (symbols), respectively, of a pentacene-based organic thin film memory transistor using poly (methyl methacrylate) (PMMA) as the insulator [7]. Figures (c) and (d) show the time evolution of the threshold voltage during the experiments (a) and (b), respectively.The authors acknowledge support from the project PID2022-139586NB-44 funded by MCIN/AEI/10.13039/501100011033 and by European Union NextGenerationEU/PRTR.

Meta-Analysis Shows Trauma Memories in Posttraumatic Stress Disorder Lack Coherence: A Response to Taylor et al. (2022)

Taylor et al. reported that in healthy participants, memories of traumatic and comparison films did not differ in coherence. The lack of a group diagnosed with posttraumatic stress disorder (PTSD) and limitations of the trauma-film paradigm mean that their design is unable to directly test predictions made by clinical theories of PTSD. Contrary to what Taylor et al. claimed, there is convincing evidence for trauma memories in PTSD being incoherent or disorganized. Meta-analysis demonstrated a strong positive association between PTSD and memory incoherence/disorganization, moderated by the effect of the methods chosen to assess disorganization.

Electrochemical synthesis of donor-acceptor triazine based polymers with halochromic and electrochromic properties

Two triazine monomers substituted with aromatic α,β unsaturated ketones (chalcones) as connecting arms, holding triphenylamine or carbazole ending groups, were by the first time synthesized using commercial and inexpensive starting materials in just two steps. Triphenylamine and carbazole groups were strategically introduced in order to allow electrochemical polymerization and redox activity of the obtained films. The chalcone, together with the triphenylamine or carbazole outer groups, give rise to the formation of a donor-acceptor systems, allowing the generation of photoinduced intramolecular charge transfer (ICT) electronic transitions and providing basic sites for protonation. Because of the star-like chemical structure of the used triazine, electrochemical polymerization of these monomers conducted to the formation of hyperbranched structures. The polymeric materials exhibited not only electrochromic properties but also showed a halochromic behavior. Spectroelectrochemical studies of the films showed different colorations in the three redox states (neutral, semioxidized and fully oxidized). The color changes are fast and easily detected by the naked eye. Electrochemical parameters such as optical contrast, coloration efficiency, optical memory, and long-term stability for both films were obtained and compared. A quasi-solid window-type electrochromic device was assembled using the electrogenerated polymer with the best electrochromic performance and stability. Moreover, the triphenylamine based polymer showed reversible color changes upon acid-base vapor exposure cycles, demonstrating that this polymer can be used not only in electrochromic devices but also in acid vapor sensors.

Carbon quantum dots boosted resistive switching and magnetic properties in Co3O4-based memory devices

Carbon quantum dots (CQDs) could create opportunities of modulating resistive switching behaviors due to their unique electrical performance. Here, CQDs are introduced to enhance switching uniformity and magnetic properties in Co3O4 thin film memory devices. Compared with the pure Co3O4-based device, the device with CQDs exhibited better performance, such as a reduced initialization voltage, uniform distribution of Set and Reset voltages, stable endurance behavior, and enhanced magnetization performance. The fitting results of current-voltage curves showed that the low-resistance states and high-resistance states of the devices obey Ohmic conduction and Schottky emission, respectively. The improvement in resistive switching properties is ascribed to the formation and rupture of confined conductive filaments due to that CQDs enhanced the local electric field, which can efficiently guide the filament growth and suppress the randomness of filament growth. Magnetization modulation associated with resistive switching involves in the variation of oxygen vacancies concentration and the conversion between Co2+ and Co3+. The present study exhibits an effective path to enhance resistive switching and magnetic properties, which shows promising application to design multifunctional electro-magnetic integrated devices.

Unwieldy matter: Liquid landscapes of memory in postdictatorship Chilean film

This article considers the haunting presence of the Pacific Ocean in two films about Southern Chile that respond to the aftermath of the Pinochet dictatorship (1973–90). I build from the premise that the heterogeneous materiality of landscapes can provoke reflection on multiple entangled histories, memories and hauntings, potentially enabling a counter-hegemonic form of historiography. Water itself is rarely analysed as ghostly matter. Its liquid materiality resists the emplacing of memorials or the accumulation of human-made debris. And yet, in the documentary El Botón de Nácar (The Pearl Button) (2015) and the narrative film La Frontera (The Frontier) (1991), water is the agglutinating presence that places different pasts in dialogue. Through my analysis, I explore the films’ engagement with the complex temporalities and cultural connotations of the ocean in Southern Chile – the cyclical movement of tides, the inevitability of catastrophic tsunamis and the enduring currents between islands that are invisible to the tourist gaze. I argue that in engaging with these temporalities, the films open alternate ways of thinking about time, history, truth and justice in the Chilean ‘transition to democracy’. This disruption makes room for histories of Indigenous survival, transnational solidarity, natural disaster and ecological destruction that are often absent or erased from postdictatorship memory culture.

Masculinity and transfemininity: Evidence in the film "Memories of My Body"

As a distinct field of research, so-called transfemininity studies can be used for the purposes of creating strategic coalitions and exploring specificities and differences. This study aims to explore the life journey of Arjuna (Juno), a man who is also a trans feminist, through the perspective of masculinity studies. The sub focuses of this research include: 1) transfemininity, physical transformation 2) and socio-psychological transformation. This research is interpretive qualitative research that verbally narrates data in the film Memories of My Body which was broadcast in 2019 as the data source. The results of the study show that Juno as the main character is caught between past trauma, his profession as a Lengger dancer, his sexual orientation and being liked by other men. Not yet finished making peace with himself, the people around him also add to the chaos with the end of his return to the beginning, trans-feminity – masculinity. Gender and sex as the other side of the coin are simple constructs, so future studies should be carried out to provide additional insights into the gender identities that have been internalized, reproduced, and possibly opposed by 'women' in everyday life in the social environment.

The effectiveness of two novel approaches to prevent intrusions: A pilot study comparing Tetris_dualtask and imagery rescripting to control

Background and objectivesPost-traumatic stress disorder (PTSD) is a global health problem. Although effective treatments for it exist, early interventions that prevent PTSD from developing are lacking. The aim of this pilot analogue trauma study was to compare the effects of two potential early intervention strategies, namely Tetris_dualtask and imagery rescripting (IR) to a no-intervention control group on intrusion frequency and the vividness and emotionality of aversive film memory. MethodsSixty healthy students were subjected to the trauma film paradigm and randomly allocated to either: Tetris_dualtask, IR or no-intervention. Main outcomes were the number of film-related intrusions at one week and vividness and emotionality ratings of the most aversive film memory. Secondary outcomes were PTSD-like symptoms, intrusion intensity, and explicit film memory. ResultsThe Tetris_dualtask group reported significant fewer intrusions compared to the no-intervention group; whereas the IR group did not. No effect was found on vividness and emotionality ratings, PTSD-like symptoms, intrusion intensity, and explicit memory. LimitationsThe sample size was small, and analogue trauma in healthy individuals was examined, thus generalizability may be limited. Also, to increase comparability between interventions, the duration of Tetris_dualtask and IR was standardized. As a result, the IR intervention was shorter compared to other studies, which might have decreased its efficacy. ConclusionsThe results of this pilot study suggest that playing Tetris during retrieval of traumatic images, might hold potential as an early intervention strategy to reduce intrusions in the early aftermath of trauma and adversity. However, future large-scale replication research is needed.

Reframing Space: Religion, History, and Memory in the Early Documentary Film of the Yugoslav Space

Reframing Space: Religion, History, and Memory in the Early Documentary Film of the Yugoslav Space

Dealing with the post-war menace: Creating transnational film memories in the shadow of the Holocaust

Traditional scholarship in social film history views groups of films from a certain time period as encapsulations of the overriding national mindset of that time. However, film scholarship has challenged this notion of what sociologists term ‘collective memory’, insisting instead that a wider range of films be included and several ‘collective memories’ be formulated in order to broaden the understanding of time-specific societal beliefs. In addition, research in memory studies has challenged the insistence on ‘national memories’, preferring instead the exploration of ‘transnational memories’. Most prominent among transnational memory scholarship is the work being done on the Holocaust. This article examines four films produced in three different national cinemas from the early post-war period (1946–49), all of which deal with the aftermath of the Holocaust in some way. Analysing these four films (The Murderers Are among Us, Rotation, The Stranger and The Third Man) and these three national cinemas (East Germany, America and Great Britain) shows how a specific transnational event such as the Holocaust can produce several aesthetic and narrative signifiers internationally while also being specifically formulated to meet local, national sensibilities.

Resisters

Resisters is an oppositional essay film, located in Berlin and addressed to Rosa Luxemburg, the Marxist Revolutionary who was assassinated in Berlin in 1919. The key analytic approaches are located within the framework of film studies, trauma and memory studies, autobiography and theories of place, space and spectatorship. The use of hybrid cinematic strategies of critical realism and poetic re-imagining, brings the force of memory and history into the present to encourage reflection and resistance and enables the circumvention of extensive use of archive footage and exposition.

Can Adaptations Create Dialectical Sites within the Skopos Theory? An Exploratory Study of Inconsolable Memories and Memories of Underdevelopment

This is an exploratory study of the adaptation of the novel Inconsolable Memories (1965) by Edmundo Desnoes into the film Memories of Underdevelopment (1968) by Tomas Gutiérrez Alea under the Skopos theory. This study is a part of a larger ongoing investigation into the cinema of Gutiérrez Alea, in which the researcher is looking at the various techniques he utilizes across his films to generate a social dialectic. The study is located in the skopos defined by Gutiérrez Alea – diminishing the role of the cultural archetypes such as patriarchy and identification with the colonizer that were deeply ingrained in the Cuban people, which he felt, were hampering the continuous progress of the socialist revolution. Here, I’m exploring the strategies he uses in the process of creating a dialectical text as a means of social reform. Gutiérrez Alea has created the adaptation through a collaboration between himself and the author of the novel, Edmundo Desnoes. The study hopes that this collaboration may also reveal a dialectical relationship under the same skopos between the two texts themselves, and the manner in which they interact and modify each other.

«Экранизация» памяти о советской космонавтике: (вос)производство образов в современном российском космическом кино

This article is devoted to the analysis of the content and pragmatics of the memory of the Soviet space program in contemporary Russian cinema. The relevance of the problem is connected with the fact that in recent years the «cosmos» has again become a stable object of social imagination and an attractive setting for the mass media. Memories of Soviet cosmonautics feature prominently in modern Russian culture. This article, referring to full-length Russian films of the 2010s, considers the cinematographic representations of the Soviet space past as memory practices. Studying them with an emphasis on the semiotic, narrative, and discursive realities of films and images offers interpretations of the past that are relevant in the concrete historical conditions of socio-cultural production. The materials of the study showed that the film history of Soviet cosmonautics has two memory frames. The heroic image of Soviet cosmonautics embodied in a specific formula of historical cinema produces a kind of restoration of the Soviet patriotic canon turning the image into an inspiring symbol of history. The revision of images of the past also leads to the release of symbolic meanings attached to the Soviet space program, which allows film memory to become not a static snapshot of the past, but a dynamic cultural force.

Film Studio as an Institution for War Memory? “Authoritative Viewers” and the Soviet Production of Cultural Trauma (1960–1980s)

The institutional approach in memory studies implies the study of stable organizational structures responsible for the production of cultural memory. Addressing the problem of late-Soviet institutions of memory of the Great Patriotic War in the 1960s-1980s, the author considers the film studio, using “Lenfilm” as an example, as a special institution of memory and cultural trauma of the war. Based on institutional sources (script files, artistic councils, etc.), the author proposes to study the production of Soviet films about the war as the interaction of a complex system of conflicting “authoritative viewers” who had (relative) autonomy, functions, and a different type of authority in judging the past – the “power of memory». The author substantiates a typology of such “memory power” (“author power”, “studio power”, “power of the cultural bureaucracy”, “party power”, “military power”, “corporate power”, and “media power”) and summarizes the main properties inherent in the system of cultural production that influenced the film memory of the war in the “long 1970s” – its stability, “institutional opacity”, “constant bargaining”, overlapping party-bureaucratic control, contestation and defense of the “autonomy of the author”.

A imagem-movimento sob palimpsestos visuais nas Escolas de Samba do Rio de Janeiro

The existence of a “cinema spirit”, a transcendent essence of movement-image, characterizes the hypermodernity (Lipovetsky e Serroy 2009). In a world simultaneously phagocytosed by cinema and cinephagic itself, the seventh art composes the imaginary of all humanity and integrates the aesthetic unconscious in the 21st century. In this context, cinema can be considered as a matritial form that is expressed in other practices and representations. The influence of film culture is also evidenced in the parades of samba schools in Rio de Janeiro: from metropolitan robots to superheroes, the show repeatedly presents multiple references - textual or visual - to cinema, and plays an important role in the consolidation and transmission of film memory in Brazil. This article proposes, therefore, a reflection on the relations of intertextuality between the parades of the samba schools of Rio de Janeiro and cinematography, in order to understand the various plans according to which the carnival image presents itself as a palimpsest (Genette 1989) of the cinematographic image.

How to process P(VDF-TrFE) thin films for controlling short circuits in flexible non-volatile memories

Severe electrical shorting is one of the biggest challenges for the development of flexible non-volatile ferroelectric memories with low operation voltage. In this work, short circuits in flexible ferroelectric capacitors based on copolymer poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)], were explicitly investigated. It was found that processing conditions of P(VDF-TrFE) films have huge effects on electrical shorting conditions. Both deciding factors such as drying temperatures, solvent evaporation rates, and solution concentrations, and plausible factors such as post-drying thermal annealing, were clearly identified. These deciding factors were found to affect short circuits by altering the film porosity, surface roughness, and defect conditions in P(VDF-TrFE) thin films. The detailed correlation of these factors with film porosity were established and explained within the framework of liquid-liquid phase separation. The correlation with the surface roughness and defect conditions were explained with Marangoni convection. The net effects of these factors on electrical shorting conditions are rather complicated because a favorable factor with regards to film porosity may be detrimental in terms of surface roughness and/or defects. So these factors have to been carefully tailored to control short circuits and generate high yields in P(VDF-TrFE) thin film memory devices. Comparative study shows that drying at 80 °C in open air is the optimal condition for processing P(VDF-TrFE) thin films from PGMEA solution. Under this optimal drying condition, a yield of 76% was achieved from large-area devices of about 200 μm × 200 μm with thin P(VDF-TrFE) films of about 200 nm processed with roll-2-roll compatible techniques on plastic substrates. An effective two-step approach to manufacturing P(VDF-TrFE) layers for ferroelectric capacitors with low operation voltage but high yields, is presented. The key information gained from this work on ferroelectric capacitors could be generalized to another type of ferroelectric memories, namely ferroelectric field effect transistors. So it provides researchers and engineers a general guideline on how to control short circuits by processing P(VDF-TrFE) thin films for flexible non-volatile memories.

Ferroelectric Memory Based on Topological Domain Structures: A Phase Field Simulation

The low storage density of ferroelectric thin film memory currently limits the further application of ferroelectric memory. Topologies based on controllable ferroelectric domain structures offer opportunities to develop microelectronic devices such as high-density memories. This study uses ferroelectric topology domains in a ferroelectric field-effect transistor (FeFET) structure for memory. The electrical behavior of FeFET and its flip properties under strain and electric fields are investigated using a phase-field model combined with the device equations of field-effect transistors. When the dimensionless electric field changes from −0.10 to 0.10, the memory window drops from 2.49 V to 0.6 V and the on-state current drops from 2.511 mA to 1.951 mA; the off-state current grows from 1.532 mA to 1.877 mA. External tensile stress increases the memory window and off-state current, while compressive stress decreases it. This study shows that a ferroelectric topology can be used as memory and could significantly increase the storage density of ferroelectric memory.

Perhydropolysilazane Charge‐Trap Layer in Solution‐Processed Organic and Oxide Memory Thin‐Film Transistors

AbstractThe charge trapping property of spin‐coated perhydropolysilazane (PHPS) layers for solution‐processed organic and oxide thin film memory transistors is demonstrated. The nitrogen content within the PHPS layer is decreased by increasing the annealing temperatures from room temperature to 450 °C. The PHPS layer added to the SiO2 gate insulator in the charge trap memories (CTMs) shows good memory functionalities which are electrically programmable, and is erased either electrically or optically depending on the semiconductor used. The stored or erased charges in the p‐type semiconductor‐based CTM result in relatively large threshold voltage shifts (∆VTH > 60 V) and large memory on‐ and off‐current ratio (IM,ON/IM,OFF > 103) with the respective memory output current extrapolated to 108 s. The n‐type CTM shows ∆VTH ≈ 20 V, IM,ON/IM,OFF of 0.5 × 103 and is extrapolated to 1015 s. It is concluded that the origin of the charge‐traps in both the p‐type and n‐type CTMs mainly originates from the PHPS charge trap layer (CTL) and greatly occurs in highly concentrated nitrogen PHPS layers. There is a high possibility of using the PHPS CTL in a wide variety of cost‐effective CTMs even with high temperature processed semiconductors.

Reminiscences – a space of memory (Based on the film Childhood Memories by Elisabeta Bostan)

Ion Creangă’s “Childhood Memories”, the most complex and significant work of the classic of Romanian literature, has so far known a single screening, that of the director Elisabeta Bostan from Romania. The film, with the same title, highlights a landscape as authentic as possible of the time, morals, customs and traditions and reflects the national identity. Or else, the memories of the writer, the main character of the film, about his childhood, his native village, villagers, etc., remain a living expression of the time. The drama organically combines two timeframes and spaces: that of Nică’s childhood, spent in the picturesque landscapes of Humulești, and the second that of the writer Ion Creangă, who listed his memories in the “bojdeuca (hut)” from Țicău. The director remains faithful to Creanga’s text, to the same colorful language full of expressions characteristic of Moldovan speech, and creates a universe similar to that of the mid-nineteenth century. The film Memories from Childhood (1965), considered by critics to be the “bridgehead of screening”, remained “in the English Academy and the Los Angeles Museum of the Arts – as a reference film in the field of screenings”.

(Invited) Ferroelectric Hafnium Oxide for Non-Volatile Memory Applications: From Single Capacitors to Memory Arrays

This year marks the 10th anniversary of the public announcement of the discovery of ferroelectricity in HfO2-based thin films. Tremendous strides have been made in both the physical understanding and the technological use of ferroelectric HfO2. These unique fluorite-structured ferroelectrics have outstanding potential for commercial applications due to their scalability, CMOS-compatibility, and facile manufacturability. Such advantages make ferroelectric HfO2 particularly attractive for nonvolatile memories technologies such as ferroelectric random access memory (FRAM) and ferroelectric field effect transistors. Due to the wide variety of conditions in which ferroelectricity can emerge in HfO2 thin films, there has been a vast effort by the international scientific community to enhance and optimize the ferroelectric properties using a wide variety of approaches. Advancements in thin film ferroelectric capacitor and memory array technologies are therefore progressing rapidly.The structural properties of HfO2 are a major focal point for technology development because the competition between several crystalline phases in HfO2 thin films can have a major impact on device performance. For thin film memory capacitors, stabilizing the polar orthorhombic phase and eliminating secondary paraelectric phases is paramount in achieving robust polycrystalline HfO2 ferroelectrics. Doping and the presence of a capping electrode during crystallization have been extensively demonstrated to influence the emergence and stability of the ferroelectric orthorhombic phase. Greater attention has been placed recently on the thin film growth conditions in atomic layer deposition and physical vapor deposition, especially with regard to the oxidation conditions that have been shown to have a substantial impact on the device performance of ferroelectric HfO2 and Hf0.5Zr0.5O2 capacitors. Composition, film growth, and the crystallization processes are critical aspects for thin film ferroelectric capacitor development and the latest developments will be comprehensively reviewed in the context of how the material properties relate to nonvolatile memory performance.Developments in thin film HfO2 ferroelectric capacitors are now coming to fruition with the emergence of ferroelectric random access memory arrays and demonstrators. Thin film ferroelectric HfO2 based capacitors are successfully being demonstrated in back-end-of-line (BEOL) processes at the 130nm CMOS technology. The performance of these early demonstrator memory arrays show very promising long term data retention, large memory windows with good statistical distributions, and projections for area scaling to nanoscale dimensions. The transition from large-scale micron-sized laboratory devices to smaller scale integrated capacitors has proven to be a major step forward in endurance cycling with >1011 cycles being reported in memory arrays. The most recent integration of thin film ferroelectric HfO2 capacitors into FRAM memory arrays and what future developments are expected for HfO2 ferroelectric random access memories will be presented. Figure 1

Traumatic Insight on Film Memory: Forced Assimilation in the Focus of Post-totalitarian Bulgarian Documentaries

Documentaries cover the subject of the extremely tragic processes of forced assimilation of Muslim population in Bulgaria in different ways. During the Communist regime, they feature the negative political visions. Social engineering in the totalitarian state aimed at confessional unity of the nation and this process was especially intense during the 1980s. Documentaries were a part of the government manipulative tools that targeted revival of the communist nationalism and an apprehensive play on the strings of patriotism. Cultural propaganda covered up repression, assaults, forced change of names, forced deportation, internment in prison camps, harassment of intellectuals from the Muslim community, and human rights violation. After 1989, Bulgarian filmmaking started interpreting this traumatic past in a different way, making a reassessment of history. Documentaries also took an active part in the debate on totalitarianism, using the screen to throw light on the political crimes. Beyond any dispute, one of the most painful subjects is the violence against Muslim communities that escalates to genocide. The subject of assimilation was more intensely covered during the 1990s and in the beginning of the Millennium. During the last decade, it gradually faded away and young authors today even neglect it. Although many good films have been made, we still get the feeling of insufficiency and understatement. The cinematic interpretations reactivate and question the traumatic memory, and further diagnose society. Quality documentary filmmaking always provides a multifaceted image of the past, preserves memories, and manages to aestheticize history in opposition to the trivial media images of the trauma. This paper analyses the genre and typological patterns specific for post-totalitarian Bulgarian documentaries. The focus of the study falls on leading authors, such as Maria Trayanova, Tatiana Vaksberg, Ivan Rossenov, Adela Peeva, Iglika Trifonova, Antony Donchev, Stanislava Kalcheva, Irina Nedeva and Andrey Getov, Dimitar Kotzev-Shosho. Two imagery trends are mainly identified: 1) documentary investigation with reconstruction of historical chronology and handling extremely valuable archives; 2) domination of the apprehensive portraiture genre, where personal records of events shape the picture of events in the past and track the consequences in the present. So far, Bulgarian film studies lack any full comparative study of the screen interpretation of assimilation processes before and after 1989.