Near unity ideality factor and Shockley-Read-Hall lifetime in GaN-on-GaN p-n diodes with avalanche breakdown

Textbook-like device characteristics are demonstrated in vertical GaN p-n diodes grown on bulk GaN substrates. These devices show simultaneously an avalanche breakdown voltage (BV) of >1.4 kV under reverse bias, an ideality factor plateau of ∼2.0 in a forward bias window followed by a near unity ideality factor of 1.1, which are consistently achieved over a temperature range of 300–400 K. At room temperature (RT), the diode with a mesa diameter of 107 μm showed a differential on-resistance R_on of 0.12 mΩcm², thus resulting in a record figure-of-merit BV²/R_on of ∼16.5 GW/cm², which is the highest ever demonstrated in any semiconductors. Analytical models are used to fit experimental I-Vs; based on the recombination current with an ideality factor of ∼2.0, a Shockley-Read-Hall lifetime of 12 ns is extracted at RT with an estimated recombination center concentration of 3 × 10¹⁵ cm⁻³.