Rajan (Raj) Kumar is a Lecturer in the Materials Science and Engineering Department at Stanford University. He teaches a variety of core undergraduate courses, including both lecture and laboratory sections. Raj enjoys discussing fundamental materials science concepts with students and strives to help them develop strong research and communication skills.

Raj received his both his BS (Northwestern) and his PhD (UC Berkeley) in Materials Science and Engineering. During his PhD, Raj studied electrochemical energy storage devices with an emphasis on developing printable batteries for integrated electronic systems. He also completed part of his PhD at SLAC National Accelerator Laboratory through the Department of Energy SCGSR Fellowship. As a graduate student, Raj received the UC Berkeley Teaching Effectiveness Award and Outstanding Graduate Student Instructor Award. He also led workshops on effective teaching strategies for first-time graduate student instructors.

Academic Appointments

2020-21 Courses

All Publications

  • Scaling Printable Zn-Ag2O Batteries for Integrated Electronics ADVANCED ENERGY MATERIALS Kumar, R., Johnson, K. M., Williams, N. X., Subramanian, V. 2019; 9 (13)
  • Scalable, High-Performance Printed InOx Transistors Enabled by Ultraviolet-Annealed Printed High-k AlOx Gate Dielectrics ACS APPLIED MATERIALS & INTERFACES Scheideler, W. J., McPhail, M. W., Kumar, R., Smith, J., Subramanian, V. 2018; 10 (43): 37277–86


    Inorganic transparent metal oxides represent one of the highest performing material systems for thin-film flexible electronics. Integrating these materials with low-temperature processing and printing technologies could fuel the next generation of ubiquitous transparent devices. In this work, we investigate the integration of UV-annealing with inkjet printing, demonstrating how UV-annealing of high- k AlO x dielectrics facilitates the fabrication of high-performance InO x transistors at low processing temperatures and improves bias-stress stability of devices with all-printed dielectrics, semiconductors, and source/drain electrodes. First, the influence of UV-annealing on printed metal-insulator-metal capacitors is explored, illustrating the effects of UV-annealing on the electrical, chemical, and morphological properties of the printed gate dielectrics. Utilizing these dielectrics, printed InO x transistors were fabricated which achieved exceptional performance at low process temperatures (<250 °C), with linear mobility μlin ≈ 12 ± 1.6 cm2/V s, subthreshold slope <150 mV/dec, Ion/ Ioff > 107, and minimal hysteresis (<50 mV). Importantly, detailed characterization of these UV-annealed printed devices reveals enhanced operational stability, with reduced threshold voltage ( Vt) shifts and more stable on-current. This work highlights a unique, synergistic interaction between low-temperature-processed high- k dielectrics and printed metal oxide semiconductors.

    View details for DOI 10.1021/acsami.8b12895

    View details for Web of Science ID 000449239600077

    View details for PubMedID 30298724

  • Low-Temperature-Processed Printed Metal Oxide Transistors Based on Pure Aqueous Inks ADVANCED FUNCTIONAL MATERIALS Scheideler, W. J., Kumar, R., Zeumault, A. R., Subramanian, V. 2017; 27 (14)