Research Projects

Deep-UV photodetectors (UVPDs) based on gallium oxide are not in commercial production. The main reason for it is the sub-optimal performance found in reported literature. For any commercial applications to move from the currently dominating and mature fields such as Silicon, SiC or GaN would require a huge impetus for the manufacturers (in the form of cost-effectiveness, large-scale mass production and easy integration with the existing technologies). In order to achieve this, zinc oxide based optoelectronics would have to show unmatched performance. Even though the reported gallium oxide based UVPDs were shown some technical improvement, it is important to minimize the Dark Current, Improve the Responsivity and Response Time of UVPDs. Due to the quantum confinement effect, it is found that nanostructured materials exhibit unique size dependent physical properties, which are very different from the conventional bulk materials. More importantly, the size of nanoparticles also has impact on the performance of devices. The size can affect hot electron injection by scattering, since in larger nanoparticles, the hot-electrons are more difficult to be transferred out with the limited mean free path. Meanwhile, with smaller nanoparticles, high-efficiency transition mechanism is discovering, for example, interfacial charge-transfer transition. The proposed work will involve in improving the three key characteristics of gallium oxide based UV Photodetectors. They are • Dark Current • Responsivity • Response Time The work propose to minimize the Dark Current by introducing the Schottky junctions using Ag/Au metals to offer barrier to free flow of majority charge carriers in the device which in turn reduces the tunneling effect across the depletion region. The generation –recombination current produced by the electron-hole pair due to thermal fluctuations can also be controlled by the defect trap states of Ga2O3. Responsivity of the Photodetector depends on the device architecture and photoconductive gain. Even though there are various vertical geometry configurations of photodetectors like p-n junction, p-i-n junction, Schottky Barrier, Avalanche Photodetectors available, integration of components is very big challenge. So a planar geometry MSM photodetector is gaining momentum among the scientific community across the globe. It is proposed that incorporation of metal (Au) nanoparticles into the Ga2O3 leads to alloying effect which enhances the free carrier concentration so that responsivity can be improved. Response Time of the Photodetector primarily influenced by the crystal quality of the film and diffusion of charge carriers across the junction. This can be achieved by changing the width (50-100nm) of inter digitized comb electrode Ag/Au which will limit the motion of the charge carriers across the device.