In this work, we have compared and modeled the electrical characteristics of two different geometrical structures of unintentionally doped (UID) thin film β-Ga₂O₃ based Schottky barrier diodes (SBD). It was observed that a lateral SBD structure can withstand much higher breakdown voltage compared to the vertical SBD structure, but suffers from significantly higher on-resistance, which can be explained considering the differences in their geometrical configuration. The schottky barrier height was determined from both capacitance voltage (C-V) and current density voltage (J-V) characteristics of the SBDs, which matched well among themselves and with the values reported in the literature. The C-V measurement was also used to determine the doping concentration in the β-Ga₂O₃ substrate, which agreed well with the manufacturer specifications.

Strong enhancement in a photoacoustic signal due to plasmonic absorption in Au nanostructures was measured using piezotransistive GaN microcantilevers. A pulsed 790 nm laser focused on the Au metallization of the piezotransistor resulted in a much larger photoacoustic signal compared to the non-metallized areas. Upon deposition of a 5 nm Au layer, the photoacoustic signal increased significantly for both previously metallized and non-metallized areas, while 2 nm Ni deposition decreased the photoacoustic signal, confirming the role of Au nanostructures in facilitating plasmonic absorption. Infrared microscopy images covering the boundary of Au metallized and non-metallized surfaces indicated a much larger rise in temperature of the former region with laser exposure, explaining the generation of photoacoustic signals through plasmonic absorption.

Surface work function (SWF) measurements using a piezotransistive III–nitride cantilever has been demonstrated on multiple surfaces. The minimum detectable surface potential change of 10 mV was achieved with a signal to noise ratio of 3. This method was applied to determine the surface potential changes due to exposure of 5 ppm NO ₂ in graphene and In ₂ O ₃ thin film, simultaneously with conductivity changes. The potentiometric measurements yielded 100 and 80 mV potential changes in SWFs of graphene and In ₂ O ₃ respectively, which matches very well with experimental data published earlier indicating the efficacy of this readily miniaturizable measurement technique.

Photoacoustic (PA) detection of H₂ and NH₃ using plasmonic excitation in Pt- and Pd-decorated GaN piezotransistive microcantilevers were investigated using pulsed 520-nm laser illumination. The sensing performances of 1-nm Pt and Pd nanoparticle (NP) deposited cantilever devices were compared, of which the Pd-coated sensor devices exhibited consistently better sensing performance, with lower limit of detection and superior signal-to-noise ratio (SNR) values, compared to the Pt-coated devices. Among the two functionalization layers, Pd-coated devices were found to respond only to H₂ exposure and not to NH₃, while Pt-coated devices exhibited repeatable response to both H₂ and NH₃ exposures, highlighting the potential of the former in performing selective detection between these reducing gases. Optimization of the device-biasing conditions were found to enhance the detection sensitivity of the sensors.