Dr Goutam Kumar Dalapati, Associate Professor, Department of Physics, SRM University-AP, Andhra Pradesh, published a research paper “Improvement on Photoresponse Properties of Self-Powered ITO/InP Schottky Junction Photodetector by Interfacial ZnO Passivation” in the reputed Journal of Electronic Materials, Springer. Photodetection has emerged as the key technology in contemporary science because of their wide range of applications in daily life and in industry, including astronomy, surveillance, environmental monitoring, machine vision, and cameras in smart phones. Commercial photodiodes should meet the criteria of high charge carrier mobility, small exciton binding energy, and higher stability. This intrigued Dr Goutam to indulge in the study of photodetector which is essential to improve several electrical parameters such as low power consumption, and higher sensitivity.
In this research, Dr Goutam developed a high-performance photodetector using Indium phosphide/indium tin oxide (InP/ITO) semiconductor metal junction. He explains, “Photodetection in semiconductors follows the principle of generating electron-hole pairs under incident light higher than or equal to its bandgap. In Schottky type photodiode, at thermal equilibrium, the Fermi levels of the metal and the semiconductor are equalized, and a transfer of electronic charge occurs from the semiconductor to the metal. Moreover, these charge transport properties can be simply tailored by compositional engineering, which provides plenty of space to modulate the performance metrics of the photodetectors. During my research, the atomic layer deposition of zinc oxide (ZnO) on the InP surface was found to increase the valence band offset for current conduction in the photodiode. Photoresponse properties were believed to improve through effective hole blocking by the ZnO interface layer which further prevents the surface recombination of photo-induced generated electron-hole pair. Through my research, I deciphered that the ITO/ZnO/InP photodiode exhibited a maximum photoresponsivity of 44.2 mAW−1 under a 520 nm laser irradiation with an illumination power of 1 μW at the zero bias voltage.”
For the successful implementation of the proposed ITO/ZnO/InP photodiode in the manufacturing levels, significant efforts are essential. Dr Goutam acknowledges that device to device variability must be addressed which arise from the deposition condition of the ZnO layer by atomic layer deposition. Surface defects reduction and selection of charge collecting electrodes must be optimized to improve the performance of the photodetector. Thus, Dr Goutam will dedicate his future research work to study patterned 2D graphene-based electrode to improve the performance. Also, n-type 2D MoS2 and hexagonal boron nitride (hBN) passivation will be studied by him on the III-V semiconductor surface for better photoresponsivity.