2022 Hashimoto Prize Winner - Shihab Hafiz
Shihab Bin Hafiz was born in Bogura, Bangladesh. He received his Bachelor of Science in Electrical & Electronic Engineering from Bangladesh University of Engineering & Technology (BUET) in July 2014. He completed his Master of Science in Nanoengineering at North Carolina Agricultural & Technical State University in May 2017. He started his doctoral study at New Jersey Institute of Technology (NJIT) in September 2017, where he joined Nanoelectronic Materials and Devices lab for his doctoral research under the supervision of Dr. Dong-Kyun Ko. He received his PhD in Electrical Engineering from NJIT in August 2021. He published several journal articles during his doctoral research. He published two journal articles in high impact journal namely ACS Applied Materials & Interfaces (IF: 9.229). He received Best Paper of 2019 Award for his review article published in Nano Convergence. He is currently working as Senior Process Engineer in GlobalFoundries to support the high-volume semiconductor manufacturing operation for 14nm FinFET technology.
PhD Work
Shihab’s doctoral research topic was “Colloidal quantum dot (CQD) based mid-wavelength infrared optoelectronics”. CQD based photodetectors are a rapidly emerging technology with a potential to significantly impact today’s infrared sensing and imaging technologies. To date, CQD photodetector research is primarily focused on lead-chalcogenide semiconductor CQDs which have spectral response fundamentally limited by the bulk bandgap of the constituent material, confining their applications to near-infrared (NIR, 0.7-1.0 um) and short-wavelength infrared (SWIR, 1-2.5 um) spectral regions. The overall goal of his research was to investigate a new generation of CQD materials and devices that advances the current CQD photodetector research toward the technologically important thermal infrared region of 3-5 μm, known as mid-wavelength infrared (MWIR).
In his PhD work, he analyzed electronic and optoelectronic characteristics of Ag2Se CQD
based devices by different device architectures with detailed analysis of detector performance parameters. In the first two years of his time at NJIT, he worked on demonstrating solution-processed lateral photoconductive photodetectors. He analyzed the effect of ligand exchange as well as temperature and spectral dependent photoresponses.
He then introduced vertically stacked quantum dot devices as the second device structure. This is an unique device structure, where a barrier QD layer is placed in between mid-wavelength absorber intraband Ag2Se QD layer. The insertion of barrier layer reduced dark current significantly since 1Se Ag2Se QD-1Se PbS QD conduction offset serves as a potential barrier, blocking the transport of thermally generated electrons and holes. In addition, he demonstrated improvement in detector performance parameters significantly at room temperature.
Finally, he developed an unique design of p-n heterojunction diode devices as third device structure. High performance detectors can be realized using a traditional p-n junction device design, however, the heavily-doped nature of intraband quantum dots present a new challenge in realizing diode devices. To address this challenge, he worked on a unique trait of blending two different QDs to control electrical property. His p-n junction devices showed significant improvement in the specific detectivity at room temperature due to the reduced noise current density under reverse bias operation.
Overall, his doctoral research demonstrated the feasibility of uncooled, room temperature photodetection in the MWIR with intraband silver selenide quantum dots that has the potential to impact numerous applications ranging from all-weather night vision, machine vision, biomedical imaging, to free-space optical communication.