In Situ <italic>O</italic>xide, <italic>G</italic>aN Interlayer-Based Vertical Trench MOS<italic>FET</italic> (<italic>OG-FET</italic>) on Bulk GaN substrates

Si Complies with GaN to Overcome Thermal Mismatches for the Heteroepitaxy of Thick GaN on Si

“…The gate recess utilized a sequential dry and wet etching in order to result in smooth and ≈80° slanted sidewalls and round corners at the bottom of the trench as shown in Figure b. The device transfer curves shown in linear and semi‐log plots are shown in Figure c and exhibit a device threshold voltage of ≈8 V and an I on / I off ratio of 10 7 approaching that of recently developed GaN‐on‐GaN trench‐gate MISFETs . The device output curves are shown in Figure d exhibiting good saturation characteristics and R on value of 31.5 mΩ cm 2 with a gate width of 100 µm (50 µm × 2; see the Supporting Information).…”

“…The device output curves are shown in Figure d exhibiting good saturation characteristics and R on value of 31.5 mΩ cm 2 with a gate width of 100 µm (50 µm × 2; see the Supporting Information). The modest hysteresis observed in the transfer curves (Figure S13, Supporting Information) and the relatively high R on observed for these first vertical GaN‐on‐Si trench MOSFETs can be further optimized with gate surface treatments and regrowth, and with engineering the doping profile in the drift layers . Additional work is also required for device edge termination in order to achieve high breakdown voltages in these devices.…”

GaN‐Based Vertical n‐Channel MISFETs on Free Standing Ammonothermal GaN Substrates

“…Several prominent concepts for vertical GaN transistors are considered: Current Aperture Vertical Electron Transistors (CAVETs), Regrown Semipolar channel and p ‐type gate structure, Trench‐gate MOSFET, and Vertical FinFETs . A particular challenge of the first two concepts is the epitaxial regrowth and limited blocking capability.…”

“…On the other hand, it requires a robust gate insulating layer to allow a space charge region for channel inversion and for good transport properties close to the semiconductor‐insulator interface . Improvement of both at the same time may be achieved by MOVPE regrowth of GaN channel and gate oxide in one additional step . And again, an additional epitaxial growth step is required and the threshold voltage shift is strongly dependent on the gate voltage stress .…”

“…Improvement of both at the same time may be achieved by MOVPE regrowth of GaN channel and gate oxide in one additional step . And again, an additional epitaxial growth step is required and the threshold voltage shift is strongly dependent on the gate voltage stress . Other challenges such as well‐defined epitaxial growth of n − ‐GaN/ p ‐GaN/ n ‐GaN junctions and an efficient activation of the p ‐GaN:Mg layer that limits the blocking voltage capability have to be addressed.…”