AVS 65th International Symposium & Exhibition
    Electronic Materials and Photonics Division Thursday Sessions
       Session EM-ThP

Paper EM-ThP3
Thermal Engineering for High-Power, Flexible Electronics

Thursday, October 25, 2018, 6:00 pm, Room Hall B

Session: Electronic Materials and Photonics Division Poster Session
Presenter: Katherine Burzynski, University of Dayton and Air Force Research Laboratory, Materials and Manufacturing Directorate
Authors: K.M. Burzynski, University of Dayton and Air Force Research Laboratory, Materials and Manufacturing Directorate
E.W. Blanton, Air Force Research Laboratory
N.R. Glavin, Air Force Research Laboratory
E.R. Heller, Air Force Research Laboratory
M. Snure, Air Force Research Laboratory
E.M. Heckman, Air Force Research Laboratory
C. Muratore, University of Dayton
Correspondent: Click to Email
Consumers and military personnel are demanding faster data speeds only available through fifth generation (5G) wireless communication technology. Furthermore, as wearable sensors and other devices become more ubiquitous, devices demonstrating enhanced flexibility and conformality are necessary. A fundamental challenge for flexible electronics is thermal management. Even on rigid substrates with significantly higher thermal conductivity than polymeric and other flexible substrates, the full potential of semiconducting materials is often thermally limited. The flexible gallium nitride (GaN) high electron mobility transistors (HEMTs) employed in this work are grown on a two-dimensional boron nitride (BN) release layer that allows the conventionally processed devices on sapphire wafers to be transferred using a polymeric stamp and placed onto a variety of rigid and flexible substrates. Characterization of the GaN device behavior on the as-grown sapphire wafers (prior to transfer) provide a baseline for evaluation of the thermal performance of engineered interfaces and substrates. With conventional substrates, device performance (specifically, the saturation current) is reduced when the device is transferred to polymeric substrates. The thermal dissipation is further restricted due to the addition of an adhesive layer to the substrate. Thermal imaging of devices in operation reveals that the current passing through an as-grown GaN transistor on a sapphire wafer reaches the target operating temperature at approximately five times the power of the same device transferred to a flexible substrate. Printable, thermally conductive nanocomposites integrating 1D, 2D, and 3D forms of carbon in a flexible, photocurable polymer matrix, as well as metal nanoparticles, were developed to maximize heat transfer from GaN devices. The thermal conductivity of the candidate substrate materials was measured experimentally, and the performance of devices transferred to these novel flexible composite substrates was characterized. The measured thermal data was used in computational simulations to predict flexible substrate architectures effectively promoting point-to-volume heat transfer to improve device performance. Additive manufacturing for engineered architectures of the flexible, thermally conductive substrate materials was demonstrated to substantially reduce the thermal limitation of high-power flexible electronics.