GaAs double heterostructure step recovery diode

We have designed and fabricated high speed double heterostructure step reco very diodes based on AlxGa1-xAs/GaAs heterojunctions and graded (x = 0-0.15 ) intrinsic layers. The m-V compound semiconductor layers were grown by usi ng MOVPE (Metal Organic Vapor Phase Epitaxy) technique, whereafter the diod e structure was mesa etched. The ohmic contacts were made by using Ti/Au la yers on the front contact and Ni/AuGe/Ni/Au layers on the backside. The mea sured ideality factor of the diode was 1.95, and the capacitance under forw ard bias was 108 pF, and 0.9 pF under reverse bias. The measured transition time was 50 ps.