Analysis of electrical properties in lateral Schottky barrier diode based on n-GaN and AlGaN/GaN heterostructure

In this paper, the lateral Schottky barrier diodes (SBDs) with small capacitance and low turn-on voltage (V ( on )) were fabricated on n-GaN and AlGaN/GaN heterostructure. The capacitances of lateral n-GaN SBD and lateral AlGaN/GaN SBD are 1.35 pF/mm and 0.70 pF/mm, respectively. Compared with the planar SBDs, the capacitances of lateral SBDs are reduced by about two orders of magnitude without sacrificing the performance of on-resistance (R ( on )) and reverse leakage current. For the planar and lateral n-GaN SBDs, the value of the V ( on ) is similar. However, compared with the planar AlGaN/GaN SBD, the V ( on ) of lateral AlGaN/GaN SBD is reduced from 1.64 V to 0.87 V owing to the anode metal directly contacting the two-dimensional electron gas. According to temperature-dependent I-V results, the barrier inhomogeneity of the lateral SBD is more intensive than the planar SBD, which is attributed to etching damage. The withstand voltage of SBD is a very important parameter for power electronic applications. Compared with the breakdown voltage of 73 V in the lateral n-GaN SBD, the lateral AlGaN/GaN SBDs exhibit a breakdown voltage of 2322 V. In addition, we found that Schottky contact introduces anode resistance (R ( A )) by analysing the R ( on ) distribution of lateral SBDs. The experimental results also show that the R ( A ) of lateral n-GaN SBD and lateral AlGaN/GaN SBD are 10.5 omega mm and 9.2 omega mm respectively, which are much larger than the ohmic contact resistance due to worsening anode contact by metal-induced gap states.