Interfacial Impurities and Their Electronic Signatures in High‐Voltage Regrown Nonpolar m‐Plane GaN Vertical p–n Diodes

Abstract

Impacts of silicon, carbon, and oxygen interfacial impurities on the performance of high‐voltage vertical GaN‐based p–n diodes are investigated. The results indicate that moderate levels (≈5 × 1017 cm−3) of all interfacial impurities lead to reverse blocking voltages (Vb) greater than 200 V at 1 μA cm−2 and forward leakage of less than 1 nA cm−2 at 1.7 V. At higher interfacial impurity levels, the performance of the diodes becomes compromised. Herein, it is concluded that each impurity has a different effect on the device performance. For example, a high carbon spike at the junction correlates with high off‐state leakage current in forward bias (≈100× higher forward leakage current compared with a reference diode), whereas the reverse bias behavior is not severely affected (> 200 V at 1 μA cm−2). High silicon and oxygen spikes at the junction strongly affect the reverse leakage currents (≈ 1–10 V at 1 μA cm−2). Regrown diodes with impurity (silicon, oxygen, and carbon) levels below 5 × 1017 cm−3 show comparable forward and reverse results with the reference continuously grown diodes. The effect of the regrowth interface position relative to the metallurgical junction on the diode performance is also discussed.