Vacuum-Induced Wrinkle Arrays of InGaAs Semiconductor Nanomembranes on Polydimethylsiloxane Microwell Arrays

Abstract

Tunable surface morphology in III-V semiconductor nanomembranes provides opportunities to modulate electronic structures and light interactions of semiconductors. Here, we introduce a vacuum-induced wrinkling method for the formation of ordered wrinkles in InGaAs nanomembranes (thickness, 42 nm) on PDMS microwell arrays as a strategy for deterministic and multidirectional wrinkle engineering of semiconductor nanomembranes. In this approach, a vacuum-induced pressure difference between the outer and inner sides of the microwell patterns covered with nanomembranes leads to bulging of the nanomembranes at the predefined microwells, which, in turn, results in stretch-induced wrinkle formation of the nanomembranes between the microwells. The direction and geometry of the nanomembrane wrinkles are well controlled by varying the PDMS modulus, depth, and shape of microwells, and the temperature during the transfer printing of nanomembrane onto heterogeneous substrates. The wrinkling method shown here can be applied to other semiconductor nanomembranes and may create an important platform to realize unconventional electronic devices with tunable electronic properties.

Fingertip skin–inspired microstructured ferroelectric skins discriminate static/dynamic pressure and temperature stimuli

“…For this measurement, various target substrates such as PDMS substrates with parallel line patterns ( D = 160 μm; P = 500 μm), sandpaper, glass, paper, and silicon substrates with different geometric patterns were used. For the discrimination of surface hardness/softness, the parallel line–patterned PDMS substrates with different moduli were prepared by adjusting the mixing ratio of PDMS base to curing agent (10:1, 15:1, and 20:1) ( 68 ).…”

Materials and Structures toward Soft Electronics

“…Spatial distribution of wave/wrinkle structures can be controlled by inducing non‐uniform strain in the substrate. The non‐uniform strain can be formed by substrate relief structures via micromolding or patterned photopolymerization . For example, a customized wrinkle design was realized by precisely controlling ridge‐guiding structures of the substrate .…”

Octopus‐Inspired Smart Adhesive Pads for Transfer Printing of Semiconducting Nanomembranes

“…Figure S9 (Supporting Information) shows that the surface roughness of the InGaAs nanomembrane was maintained after the smart‐printing process. Here, the high roughness of the InGaAs nanomembrane on the smart adhesive pad is due to the strong suction of the InGaAs nanomembrane into the hole of the smart pad due to the pressure difference, which can be recovered to its original state after transferring the InGaAs nanomembrane onto the SiO 2 /Si substrate. This complete restoration of the InGaAs nanomembrane indicates that the smart‐printing process is applicable to the transfer printing of ultrathin nanomembranes without damage or ripples in the nanomembranes.…”