Double-barrier GaN resonant tunnelling diodes with AlGaN barriers were fabricated on bulk (00▪1) single-crystal GaN substrates. Layers were grown using molecular-beam epitaxy with a rf plasma N source. Single diodes of 6µm diameter were prepared by inductively coupled plasma reactive ion etching. For many diodes clear negative differential resistance was observed around 2V with peak currents around 10kA/cm2 and a peak-to-valley ratio of about 2 at room temperature. Its observation did not depend on specific conditions of measurement; however, it slowly decays after each measurement. The mechanism behind this decay was investigated since it was obviously prohibiting the usage of GaN resonant tunnelling diodes so far. It was shown not to be caused by catastrophic breakdown of the devices.

Negative Differential Resistance in Dislocation-Free GaN/AlGaN Double-Barrier Diodes Grown on Bulk GaN. S.Golka, C.Pflügl, W.Schrenk, G.Strasser, C.Skierbiszewski, M.Siekacz, I.Grzegory, S.Porowski: Applied Physics Letters, 2006, 88[17], 172106 (3pp)