Transparent and Flexible Capacitors with an Ultrathin Structure by Using Graphene as Bottom Electrodes

Abstract

Ultrathin, transparent and flexible capacitors using graphene as the bottom electrodes were directly fabricated on polyethylene naphthalate (PEN) substrates. ZrO2 dielectric films were deposited on the treated surface of graphene by atomic layer deposition (ALD). The deposition process did not introduce any detectible defects in the graphene, as indicated by Raman measurements, guaranteeing the electrical performances of the graphene electrodes. The Aluminum-doped zinc oxide (AZO) films were prepared as the top electrodes using the ALD technique. The capacitors presented a high capacitance density (10.3 fF/μm2 at 10 kHz) and a relatively low leakage current (5.3 × 10−6 A/cm2 at 1 V). Bending tests revealed that the capacitors were able to work normally at an outward bending radius of 10 mm without any deterioration of electrical properties. The capacitors exhibited an average optical transmittance of close to 70% at visible wavelengths. Thus, it opens the door to practical applications in transparent integrated circuits.

Morphology and Thermal Properties of Calcium Alginate/Reduced Graphene Oxide Composites

“…Reduced graphene oxide (rGO) is a high-temperature resistant and environmentally friendly material with a melting point of over 4000 K [13]. It shows important application prospects in advanced materials science [14], new energy and biomedicine, and is considered to be a revolutionary material [15] for the future, making it a current research hotspot. Huang et al prepared polyvinyl alcohol/rGO nanocomposites by a solution blending method, and the results showed that the composite materials burned to form a dense and uniform carbon layer, which can prevent the thermal mass transfer and exchange of the combustible gas between the matrix material and the outside [16].…”

High‐Performance Nanostructured Flexible Capacitor by Plasma‐Induced Low‐Temperature Atomic Layer Annealing

“…To the best of our knowledge, our work shows the highest capacitance density and k-value with comparably low leakage current density level (10 −7 A cm −2 ) and decent flexibility (10 mm radius convex bending) compared with other flexible capacitors ever fabricated by ALD techniques and other low-temperature processes directly on flexible substrates including PET, PEN, PI, and PC (Table 1). [39][40][41][47][48][49][50][51] Generally, the flexible capacitor with ALD-processed dielectric layers showed higher capacitance density. For example, Zhang et al [39] fabricated flexible MIM capacitors with a surface area enhancing regime by incorporating Ag NWs into the bottom electrode composite ALD-AZO (Al-doped ZnO)/Ag NWs/sputtered AZO, which exhibited a capacitance density of 10.1 nF mm −2 at 10 kHz.…”

“…To the best of our knowledge, our work shows the highest capacitance density and k ‐value with comparably low leakage current density level (10 −7 A cm −2 ) and decent flexibility (10 mm radius convex bending) compared with other flexible capacitors ever fabricated by ALD techniques and other low‐temperature processes directly on flexible substrates including PET, PEN, PI, and PC ( Table 1 ). [ 39–41,47–51 ] Generally, the flexible capacitor with ALD‐processed dielectric layers showed higher capacitance density. For example, Zhang et al.…”

New development of atomic layer deposition: processes, methods and applications

“…More researches have been published on metal-insulator-metal capacitors using ALD [198][199][200][201]. More work on the application of ALD for capacitors has been done by different researchers looking at the growth rate, limitations and various applications on different materials [202][203][204][205][206][207]. Figure 8.…”