Directed self-assembly (DSA) emerges as one of the most promising new patterning techniques for single digit miniaturization and next generation lithography. DSA achieves high-resolution patterning by molecular assembly that circumvents the diffraction limit of conventional photolithography. Recently, the International Roadmap for Devices and Systems listed DSA as one of the advanced lithography techniques for the fabrication of 3–5 nm technology node devices. DSA can be combined with other lithography techniques, such as extreme ultra violet (EUV) and 193 nm immersion (193i), to further enhance the patterning resolution and the device density. So far, DSA has demonstrated its superior ability for the fabrication of nanoscale devices, such as fin field effect transistor and bit pattern media, offering a variety of configurations for high-density integration and low-cost manufacturing. Over 1 T in⁻² device density can be achieved either by direct templating or coupled with nanoimprinting to improve the throughput. The development of high χ block copolymer further enhances the patterning resolution of DSA. In addition to its superiority in high-resolution patterning, the implementation of DSA on a 300 mm pivot line fully demonstrates its potential for large-scale, high-throughput, and cost-effective manufacturing in industrial environment.

Block copolymer (BCP) self-assembly, as a novel bottom-up patterning technique, has received increasing attention in the manufacture of nanodevices because of its significant advantages of high resolution, high throughput, low cost, and simple processing. BCP self-assembly provides a very powerful approach to constructing diverse nanoscale templates and patterns that meet large-scale manufacturing practices. For the past 20 years, the self-assembly of BCPs has been extensively employed to produce a range of nanodevices, such as nonvolatile memory, bit-patterned media (BPM), fin field-effect transistors (FinFETs), photonic nanodevices, solar cells, biological and chemical sensors, and ultrafiltration membranes, providing a variety of configurations for high-density integration and cost-efficient manufacturing. In this review, we summarize the recent progress in the fabrication of nanodevices using the templates of BCP self-assembly, and present current challenges and future opportunities.

Directed self-assembly of block copolymers (BCPs) enables nanofabrication at sub-10 nm dimensions, beyond the resolution of conventional lithography. However, directing the position, orientation, and long-range lateral order of BCP domains to produce technologically-useful patterns is a challenge. Here, we present a promising approach to direct assembly using spatial boundaries between planar, low-resolution regions on a surface with different composition. Pairs of boundaries are formed at the edges of isolated stripes on a background substrate. Vertical lamellae nucleate at and are pinned by chemical contrast at each stripe/substrate boundary, align parallel to boundaries, selectively propagate from boundaries into stripe interiors (whereas horizontal lamellae form on the background), and register to wide stripes to multiply the feature density. Ordered BCP line arrays with half-pitch of 6.4 nm are demonstrated on stripes >80 nm wide. Boundary-directed epitaxy provides an attractive path towards assembling, creating, and lithographically defining materials on sub-10 nm scales.

Impact ionization effect has been demonstrated in transistors to enable sub-60 mV dec⁻¹ subthreshold swing. However, traditionally, impact ionization in silicon devices requires a high operation voltage due to limited electrical field near the device drain, contradicting the low energy operation purpose. Here, we report a vertical subthreshold swing device composed of a graphene/silicon heterojunction drain and a silicon channel. This structure creates a low voltage avalanche impact ionization phenomenon and leads to steep switching of the silicon-based device. Experimental measurements reveal a small average subthreshold swing of 16 µV dec⁻¹ over 6 decades of drain current and nearly hysteresis-free, and the operating voltage at which a vertical subthreshold swing occurs can be as low as 0.4 V at room temperature. Furthermore, a complementary silicon-based logic inverter is experimentally demonstrated to reach a voltage gain of 311 at a supply voltage of 2 V.

Graphene is one of the most promising nanomaterials with many extraordinary properties and numerous exciting applications. In this work, a green, facile, and rapid method was developed to prepare graphene directly from common biomass materials such as banana peels, cantaloupe peels, coconut peels, and orange peels by using concentrated solar radiation. The basic principle of this method is photothermal conversion. On a sunny day, the sunlight was concentrated by a biconvex lens to form a focused light spot with a high temperature above 1000 °C, which can directly convert fruit peels into graphene nanosheets within 2-3 s. The product is named concentrated-solar-induced graphene (CSIG) based on the process employed to generate it. The resulting CSIG was characterized using a range of analytical techniques. The Raman spectrum of the CSIG displayed two distinct peaks corresponding to the D and G bands at ∼1343 and ∼1568 cm^-1, respectively. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction were used to confirm that the CSIG consists of a few layers of turbostratic graphene nanosheets. Atomic force microscopy characterization revealed that the CSIG nanosheets have a thickness of ∼4 nm. The antibacterial potential of the CSIG was also explored. The CSIG had a strong inhibitory effect on the growth of Escherichia coli. This simple, green, and straightforward method for producing graphene may open a new route for turning waste into useful materials: an inexhaustible and pollution-free natural resource can be readily exploited by using a solar tracker-lens system for the large-scale production of graphene materials directly from low-cost biomass materials.