Hydrophobic, self-doped conjugated polyelectrolytes (CPEs) are introduced as highly stable active materials for organic electrochemical transistors (OECTs). The hydrophobicity of CPEs renders films very stable in aqueous solutions. The devices operate at gate voltages around zero and show no signs of degradation when operated for 10 cycles under ambient conditions. These properties make the produced OECTs ideal devices for applications in bioelectronics.

A pivotal issue for the fabrication of electronic devices on epitaxial graphene on SiC is controlling the number of layers and reducing localized thickness inhomogeneities. Of equal importance is to understand what governs the unintentional doping of the graphene from the substrate. The influence of substrate surface topography on these two issues was studied by work function measurements and local surface potential mapping. The carrier concentration and the uniformity of epitaxial graphene samples grown under identical conditions and on substrates of nominally identical orientation were both found to depend strongly on the terrace width of the SiC substrate after growth.

The electrical characteristics of Au/3C-SiC Schottky diodes were studied as a function of contact area. While the larger diodes were characterized by conventional current-voltage measurements, conductive atomic force microscopy was used to perform current-voltage measurements on diodes of contact radius down to 5 μm. The results show that the Schottky barrier height increases upon reducing the contact area, and for the smallest diodes the value approaches the ideal barrier height of the system. The results were correlated with defects in the 3C-SiC and an analytical expression was derived to describe the dependence of the barrier height on the defect density.

Using environmental scanning Kelvin probe microscopy, we show that the position of the Fermi level of single layer graphene is more sensitive to chemical gating than that of double layer graphene. We calculate that the difference in sensitivity to chemical gating is not entirely due to the difference in band structure of 1 and 2 layer graphene. The findings are important for gas sensing where the sensitivity of the electronic properties to gas adsorption is monitored and suggest that single layer graphene could make a more sensitive gas sensor than double layer graphene. We propose that the difference in surface potential between adsorbate-free single and double layer graphene, measured using scanning kelvin probe microscopy, can be used as a noninvasive method of estimating substrate-induced doping in epitaxial graphene.