GaN drift-layer thickness effects in vertical Schottky barrier diodes on free-standing HVPE GaN substrates

Vertical Schottky barrier diodes (SBD) with different drift-layer thicknesses (DLT) of GaN up to 30 μm grown by metalorganic chemical vapour deposition (MOCVD) were fabricated on free-standing GaN grown by hydride vapour phase epitaxy (HVPE). At room temperature, SBD’s exhibited average barrier heights (ΦB) in the range of 0.73 eV to 0.81 eV. The effective barrier heights (ΦBeff) of SBDs with different DLT also exhibited a similar range of ΦB measured at room temperature. The measured reverse breakdown voltages (VBD) of SBDs increased from 562 V to 2400 V with an increase in DLT. The observation of high VBD of SBDs could be due to the lower effective donor concentration (7.6×1014 /cm3), which was measured from SIMS analysis. The measured VBD of 2400 V is the highest value ever reported for a 30 μm DLT vertical GaN SBD without additional edge termination or field plate (FP).