The bond dissociation energy of atomically thin van der Waals (vdW) semiconductors is relatively weaker typically ranging 2-3 eV, compared to elemental semiconductors, thus one can immediately access to direct light-lattice interactions with conventional light sources for spectroscopy [1]. In this talk, we discuss a series of our recent works on selective light-lattice interactions in atomically thin vdW semiconductors toward realization of two-dimensional (2D) integrated circuitry (ICs). Complementary doping on a semiconductor is an elementary process to build monolithic ICs. However, for 2D vdW semiconductors, the construction of monolithic ICs remains challenging because of the absence of a locally selective doping method. Toward this end, we first demonstrated a simple method of “programmable writing” of various 2D ICs on atomically thin vdW semiconductor host lattice by exploiting a novel concept of self-aligned doping with a scanning light probe, in analogy to ion implantation in Si CMOS technology [2]. Then, we discovered that such direct light-lattice interactions can be selective and reversible with the choices of light colors, i.e. “reconfigurable” photo-induced doping using different photon energies, which were supported by visual and spectroscopic evidence of individual n- and p-dopants at the atomic scale [3]. This simple doping enables one to repeatedly inscribe and erase the carrier types and concentrations of an identical semiconductor channel at room temperature with conventional light sources. We indeed showed diverse CMOS ICs using such light probes, including n-p-n (p-n-p) bipolar junction transistor amplifiers, radial p-n photovoltaic cells and reconfigurable CMOS inverter-switches [2-3]. At the end, we discuss another recent example of atomically thin photo-memtransistors, which can be viewed as an atomistic synapse networks in hardware-based artificial neural networks technology [4].    

References:

[1] “Identification of point defects of atomically thin transition-metal dichalcogenide semiconductors as active dopants”, Seung-Young Seo et al., Nano Letters AOP (2021).

[2] “Writing monolithic integrated circuits on a two-dimensional semiconductor with a scanning light probe”, Seung-Young Seo et al., Nature Electronics, 1, 512 (2018)

[3] “Reconfigurable photo-induced doping of two-dimensional van der Waals semiconductors using different photon energy” Seung-Young Seo and Gunho Moon et al., Nature Electronics, 4, 38 (2021)

[4] “Atomistic synapse networks on atomically thin van der Waals photo-memtransistors”, Gunho Moon et al., Submitted (2021)