The structural, vibrational, and optoelectronic properties of sol–gel synthesized Zn1−x(Al0.5Si0.5)xO nanoparticles were investigated. The X-ray diffraction studies of the samples confirmed the hexagonal wurtzite phase with the space group P63mc. No significant changes were observed in the lattice parameters. The increase in the intensity of $E_{{\rm{high}}}^2$ Raman mode observed at 438 cm−1 indicates a decrease in the crystallite size. The reduction in the deep-level emission band with the introduction of Al/Si indicates a decrease in intrinsic defects for the codoped sample. A unique electron paramagnetic resonance signal at g= 1.96 follows the same trend as the green luminescence, and its evolution was shown to probe the oxygen vacancy concentrations. I–V characteristics curve confirm the increase in the conductivity for the codoped samples. To evaluate the role of surface defects, ultraviolet photoresponse behavior as a function of time was also studied, and an increase in the photocurrent was observed. The slow decay and rise in the photocurrent are because of multiple trapping by interstitial defects. A relatively faster response time was observed with the substitution of Al/Si. It has been observed that prepared nanomaterials are suitable for optoelectronic devices.

Aluminum gallium nitride (AlGaN) metal–semiconductor–metal photodetectors were successfully fabricated with different contact materials and structures and were tested with ultrafast lasers. The experimental results were compared with the finite element simulations based on APSYS and showed consistent trend with respect to the device I–V properties and response behaviors. Persistent photoconductivity (PPC) was observed for devices with both gold and aluminum contacts and various structures, and the decay time can be longer than 10 ms. The response time and responsivity were found to be affected by the bias voltage, operating temperature, and incident power. The mechanism behind the long decay time is analyzed from the perspective of the materials properties and factors influencing the decay time are examined. The nature of the metal–semiconductor contact is studied to help understand the PPC effect, and the contact showed ohmic-like behavior.

Müller cells are highly permeable to potassium ions and play a major role in maintaining potassium homeostasis in the vertebrate retina during light-evoked neuronal activity. Potassium fluxes across the Müller cell's membrane are believed to underlie the light-evoked responses of these cells. We studied the potassium currents of turtle Müller cells in the retinal slice and in dissociated cell preparations and their role in the genesis of the light-evoked responses of these cells. In either preparation, the I–V curve, measured under voltage-clamp conditions, consisted of inward and outward currents. A mixture of cesium ions, TEA, and 4-AP blocked the inward current but had no effect on the outward current. Extracellular cesium ions alone blocked the inward current but exerted no effect on the photoresponses. Extracellular barium ions blocked both inward and outward currents, induced substantial depolarization, and augmented the light-evoked responses, especially the OFF component. Exposing isolated Müller cells to a high potassium concentration did not cause any current or voltage responses when barium ions were present. In contrast, application of glutamate in the presence of barium ions induced a small inward current that was associated with a substantially augmented depolarizing wave relative to that observed under control conditions. This observation suggests a role for an electrogenic glutamate transporter in generating the OFF component of the turtle Müller cell photoresponse.