Characterization of carrier behavior in photonically excited 6H silicon carbide exhibiting fast, high voltage, bulk transconductance properties

Abstract

Unabated, worldwide trends in CO2 production project growth to > 43-BMT per year over the next two decades. Efficient power electronics are crucial to fully realizing the CO2 mitigating benefits of a worldwide smart grid (~ 18% reduction for the United States alone). Even state-of-the-art SiC high voltage junction devices are inefficient because of slow transition times (~ 0.5-μs) and limited switching rates at high voltage (~ 20-kHz at ≥ 15-kV) resulting from the intrinsically limited charge carrier drift speed (< 2 × 107-cm-s−1). Slow transition times and limited switch rates waste energy through transition loss and hysteresis loss in external magnetic components. Bulk conduction devices, where carriers are generated and controlled nearly simultaneously throughout the device volume, minimize this loss. Such devices are possible using below bandgap excitation of semi-insulating (SI) SiC single crystals. We explored carrier dynamics with a 75-fs single wavelength pump/supercontinuum probe and a modified transient spectroscopy technique and also demonstrated a new class of efficient, high-speed, high-gain, bi-directional, optically-controlled transistor-like power device. At a performance level six times that of existing devices, for the first time we demonstrated prototype operation at multi-10s of kW and 20-kV, 125-kHz in a bulk conduction transistor-like device using direct photon-carrier excitation with below bandgap light.

Megavolt bremsstrahlung measurements from linear induction accelerators demonstrate possible use as a FLASH radiotherapy source to reduce acute toxicity

“…( e , f ) First tests on high gradient cavities operating at 42 kV per cell using SF 6 insulation gas; we anticipate better than twice the performance using oil insulation. ( g , h ) Testing silicon carbide switching using the optical transconductance varistor (OTV) technology 64 . …”

“…To replace the existing pulsed source, we are testing high repetition rate, single crystal, semi-insulating SiC photoswitches driven by pulsed laser diodes (Fig. 5 g–h) 64 . We have also tested and utilized a configuration that charges capacitors in parallel and selectively discharges them in series to allow output voltage variability, and hence variable control of the electron final energy over a wide range 65 .…”

Megavolt Bremsstrahlung Measurements from Linear Induction Accelerators Demonstrate Possible Use as a FLASH Radiotherapy Source to Reduce Acute Toxicity

“…To replace the existing pulsed source, we are testing high repetition rate, single crystal, semi-insulating SiC photoswitches driven by pulsed laser diodes (Fig. 5g-5h) [ 60]. We have also tested and utilized a configuration that charges capacitors in parallel and selectively discharges them in series to allow output voltage variability, and hence variable control of the electron final energy over a wide range [ 61].…”

Co-designing chip package structure on the ceramic vapor chamber for the high-conducting heat packaging

“…The power devices (e.g., SBD (Schottky Barrier Diode), MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), IGBT (Insulated Gate Bipolar Transistor), etc.) are core components in the fields of the highspeed rail, the electric vehicles, and the national defense 20,21 . Although the total consumption of power devices is not enormous, the local heat flux caused by the transistor gate's leakage current has exceeded 1000 W cm -2 .…”