Low on‐resistance of GaN p‐i‐n vertical conducting diodes grown on 4H‐SiC substrates

Abstract

We investigated the resistance of conductive AlGaN buffer layers and the current-voltage characteristics of GaN p-i-n vertical conducting diodes on n-type 4H-SiC substrates grown by low-pressure metalorganic vapor-phase epitaxy. High Si doping of the AlGaN buffer layer at the AlGaN/SiC interface produces ohmic current-voltage characteristics in spite of the large band offset between AlGaN and 4H-SiC. Owing to the optimization of the AlGaN buffer layer, a low on-resistance (R on ) of 1.12 mΩ cm 2 with high breakdown voltage (V B ) of 300 V is obtained for a GaN p-i-n vertical conducting diode on a 4H-SiC substrate, leading to the figure of merit (V B 2 /R on ) of 80 MW/cm 2 , which is larger than that for the diode with the same structure on a 6H-SiC substrate (62 MW/cm 2 ). This result indicates that 4H-SiC is preferable for fabricating GaN-based electronic devices with a low on-resistance and high breakdown voltage.

Fully Vertical GaN-on-SiC p-i-n Diodes With BFOM of 2.89 GW/cm2

“…Using the GaN-on-SiC platform also allows monolithic integration of GaN and SiC devices [8]. In the 2000s, some researchers demonstrated fully-vertical GaN-on-SiC p-i-n diodes with conductive AlGaN buffer [15]- [17]. However, there is still plenty of room for performance improvement.…”

Enhancement of breakdown voltage for fully-vertical GaN-on-Si p-n diode by using strained layer superlattice as drift layer

“…Further, these devices offer the advantages of reduced chip size and reduced production cost. Such vertical devices are typically fabricated on free-standing GaN templates and SiC substrates, which enable the growth of thick drift layer and achieving higher breakdown [5][6][7][8][9][10][11]. However, the downsides of using these substrates are that they are truly expensive and available only in small-size diameters.…”

Novel fully vertical GaN p–n diode on Si substrate grown by metalorganic chemical vapor deposition

“…6. [8][9][10][11]21,22) The Baliga's figure of merit (FOM) V 2 B =R on for the GaN vertical p-n diode was calculated to be 11.2 MW=cm 2 . The estimated critical electric field for a 1.5-µm-thick n − -GaN drift layer was 192 V=µm, which is better than previously reported values for GaN vertical p-n diodes on Si using substrate removal technology.…”