Nonvolatile Polymer Memory with Nanoconfinement of Ferroelectric Crystals

Abstract

We demonstrate significantly improved performance of a nonvolatile polymeric ferroelectric field effect transistor (FeFET) memory using nanoscopic confinement of poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) within self-assembled organosilicate (OS) lamellae. Periodic OS lamellae with 30 nm in width and 50 nm in periodicity were templated using block copolymer self-assembly. Confined crystallization of PVDF-TrFE not only significantly reduces gate leakage current but also facilitates ferroelectric polarization switching. These benefits are due to the elimination of structural defects and the development of an effective PVDF-TrFE crystal orientation through nanoconfinement. A bottom gate FeFET fabricated using a single-crystalline triisopropylsilylethynyl pentacene channel and PVDF-TrFE/OS hybrid gate insulator shows characteristic source-drain current hysteresis that is fully saturated at a programming voltage of ±8 V with an ON/OFF current ratio and a data retention time of approximately 10(2) and 2 h, respectively.

Non-volatile organic memory with sub-millimetre bending radius

“…In particular, high-performance flexible non-volatile memories based on various data storage principles such as resistive type [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] , flash 4,[25][26][27][28][29] and ferroelectric [30][31][32][33][34][35][36][37][38][39][40] hold great promise in a variety of emerging applications ranging from mobile computing to information management and communication. While the recent advances in this area are impressive, novel organic materials and electronic device structures that can be tightly rolled, crumpled, stretched, sharply folded and unfolded repeatedly without any performance degradation still need to be developed.…”

“…In a Fe-FET, the polarity of the programme/erase gate voltage determines the polarization state of the ferroelectric layer, which in turn controls the accumulation or depletion of carriers in the semiconducting channel between the source and drain electrode, giving rise to characteristic current hysteresis 32,33 . To realize extremely flexible Fe-FET devices, great care should be taken in the design/selection of organic semiconductors so as to prevent the formation of cracks during and after the application of a repetitive large mechanical stress and ensure excellent adhesion properties with the ferroelectric polymer layer to avoid delamination at interfaces.…”

“…Although significant progress has been made in improving certain characteristics of ferroelectric polymer memories [30][31][32][33][34][35] , only a few works have addressed mechanically flexible Fe-FETs in which characteristic ferroelectric switching has been examined under a relatively mild bending radius on the order of a few millimetres [36][37][38] . Besides ferroelectric memories, most of the previous non-volatile memories are categorized as bendable devices when their bending radii are much greater than 1 mm (Supplementary Table 1).…”

Fabrication of Arrays of Lead Zirconate Titanate (PZT) Nanodots via Block Copolymer Self-Assembly

“…[1][2][3][4][5][6][7] Efforts have been made by a number of research groups to realize this goal by nanoscaling ferroelectric materials using different 'top-down' and 'bottom-up' approaches. 3,[8][9][10] Fabrication of two dimensional (2D) arrays of ferroelectric nanoislands or nanodots is an ideal approach for forming isolated nanodomains, where the individual units can store physically separate bits of data. 3,5,6,8,11 Isolated singlecrystalline ferroelectric nanostructures have shown improved memory characteristics such as high polarization retention compared to their thin film counterparts, due to the presence of single ferroelectric domains, 11 and increased electromechanical displacement due the reduction of clamping effects on 90 degree domain reorientation.…”

“…3,[8][9][10] Fabrication of two dimensional (2D) arrays of ferroelectric nanoislands or nanodots is an ideal approach for forming isolated nanodomains, where the individual units can store physically separate bits of data. 3,5,6,8,11 Isolated singlecrystalline ferroelectric nanostructures have shown improved memory characteristics such as high polarization retention compared to their thin film counterparts, due to the presence of single ferroelectric domains, 11 and increased electromechanical displacement due the reduction of clamping effects on 90 degree domain reorientation. 12 Techniques such as electron beam lithography, 5,6 focused ion beam milling, 12 nanoimprint lithography, 13,14 dip-pen lithography, 15 sol-gel selfassembly [16][17][18] and templating 7,11,[19][20][21] have been used successfully to fabricate arrays of discrete nanoislands or dots.…”