Zero-bias photocurrents in highly-disordered networks of Ge and Si nanowires.

Semiconducting nanowire (NW) devices have garnered attention in self-powered electronic and optoelectronic applications. This work explores and exhibits, for the first time for visible light, clear evidence of the zero-biased optoelectronic switching in randomly dispersed Ge and Si NW networks. The test bench, on which the NWs were dispersed for optoelectronic characterization, was fabricated using a standard CMOS fabrication process, and utilized metal contacts with dissimilar work functions-Al and Ni. The randomly dispersed NWs respond to light by exhibiting substantial photocurrents and, most remarkably, demonstrate zero-bias photo-switching. The magnitude of the photocurrent is dependent on the NW material, as well as the channel length. The photocurrent in randomly dispersed GeNWs was found to be higher by orders of magnitude compared to SiNWs. In both of these material systems, when the length of the NWs was comparable to the channel length, the currents in sparse NW networks were found to be higher than those in dense NW networks, which can be explained by considering various possible arrangements of NWs in these devices.

Optimization of selection of chain amine scrubbers for CO2 capture.

In order to optimize the selection of a suitable amine molecule for CO2 scrubbers, a series of ab initio calculations were performed at the B3LYP/6-31+G(d,p) level of theory. Diethylenetriamine was used as a simple chain amine. Methyl and hydroxyl groups served as examples of electron donors, and electron withdrawing groups like trifluoromethyl and nitro substituents were also evaluated. Interaction distances and binding energies were employed as comparison operators. Moreover, natural bond orbital (NBO) analysis, namely the second order perturbation approach, was applied to determine whether the amine-CO2 interaction is chemical or physical. Different sizes of substituents affect the capture ability of diethylenetriamine. For instance, trifluoromethyl shields the nitrogen atom to which it attaches from the interaction with CO2. The results presented here provide a means of optimizing the choice of amine molecules for developing new amine scrubbers.