Ultra wide-bandgap (WBG) semiconductor Aluminum Nitride (AlN) has conventionally found use as signal filters in wireless communication devices such as cell-phones. However, with the need for higher wireless data speeds growing, AlN provides unique capability to integrate active devices such as transistors and passive devices such as filters, antennas and waveguides monolithically into one chip - increasing the efficiency and decreasing costs.
In my defense talk, I present a glimpse into the exciting developments over the past 5 years in the Jena-Xing group in developing the AlN platform for mm-wave electronics - from the physics of making an insulating material conduct, to growth of high-purity semiconductor crystals to record performance transistors. In particular, I discuss my discovery of the long-missing undoped III-nitride 2D hole gas (2DHG) in gallium nitride on AlN, and how we used these 2DHG channels and best-in-class low-resistance ohmic contacts to demonstrate the first p-channel transistor that break the GHz-speed barrier.
Main references :
● R. Chaudhuri, S. Bader, Z. Chen, D. Muller, H. Xing, D. Jena, “A polarization-induced 2D hole gas in undoped gallium nitride quantum wells”, Science (2019)
● R. Chaudhuri, Z. Chen, D. Muller, H. Xing, D. Jena, “High conductivity Polarization-induced 2D hole gases in Undoped GaN/AlN Heterojunctions enabled by Impurity Blocking Layers”, Journal of Applied Physics (2021)
● K Nomoto, R Chaudhuri, SJ Bader, L Li, A Hickman, S Huang, H Lee, T Maeda, HW Then, M Radosavljevic, P Fischer, A Molnar, JCM Hwang, HG Xing, D Jena, “GaN/AlN p-channel HFETs with I max >420 mA/mm and ~20 GHz f T / fMAX ”, IEDM (2021)
● A. Hickman, R Chaudhuri, SJ Bader, K. Nomoto, L Li, JCM Hwang, HG Xing, D Jena, “Next generation electronics on the ultrawide-bandgap aluminum nitride platform”, SST (2020)