Patterned Quantum Dot Photosensitive FETs for Medium Frequency Optoelectronics

Abstract

The use of colloidal quantum dots (CQDs) as active layers for the transistors in integrated circuits is often impeded by the poor compatibility of CQDs films with the standard lithographic processing. Successful patterning of tetrabutylammonium iodide‐treated PbS CQDs films is demonstrated on (3‐aminopropyl)triethoxysilane (APTES) functionalized glass or aluminum oxide surfaces, using lithography. Short‐channel (4 µm) field‐effect transistors (FETs) with patterned gate electrode and patterned CQDs film as active layer with electron mobility of 0.1 cm2 V−1 s−1, threshold voltage of −0.29 V, and cutoff frequency of 400 kHz are demonstrated. Furthermore, the lithographic processing does not compromise the optical properties of the film, as evidenced by the photoresponse measurements of the FETs (11.6 mA W−1 at 920 nm and 26.7 mA W−1 at 440 nm). These results further demonstrate CQDs as a potential material for optoelectronic applications, where medium frequency operation is required.

Scalable PbS Quantum Dot Solar Cell Production by Blade Coating from Stable Inks

“…Interestingly, in all of the AFM micrographs, we can see features of 15–35 nm in size, which are probably domains caused by quantum dot aggregation. These features are also clearly visible on the AFM images of PbS QD films deposited by various methods reported by various authors, for example, on films deposited by the layer-by-layer spin coating with TBAI . The formation of these aggregates can support the appearance of the peak at 0.8 eV in the absorption and PL spectra of the films in Figure .…”

High-resolution patterning of colloidal quantum dots via non-destructive, light-driven ligand crosslinking

“…While the solution processability of QDs allows low-cost production of films over a large area, it prevents conducting a secondary solution process on top of the underlying QD film. This indicates that conventional photoresistbased patterning methods are hardly applicable, unless the surface of QDs is delicately managed 26 ; the QD films would be soluble to the solvent used to apply the photoresist. Furthermore, forming patterns of different colour QDs (e.g., R, G, B patterns of QDs) side-by-side by conducting consecutive cycles of solution processing is challenging, because processing one of the QD layers is likely to damage the underlying QD patterns.…”

Patterning Quantum Dots via Photolithography: A Review

“…Loi et al first treated a substrate (aluminum oxide or glass) with a 3‐aminopropyltriethoxysilane (APTES) self‐assembled monolayer; the amino group in APTES is known to offer better adhesion with the QD film on top than with the nontreated substrate, whereas the silane group chemically bonds with the underlying aluminum oxide or glass substrate. [ 81 ] Once the QD film was coated, the original oleic acid ligands were replaced with short iodide ligands. This allowed the QD films to remain firm without delamination and cracking during the PR application (AZ nLOF 2020) and subsequent PR patterning steps.…”