THE IMPACT OF USING ALGAAS AS A CARRIER SUPPLYING LAYER IN AN INALAS/INGAAS HIGH ELECTRON MOBILITY TRANSISTOR STRUCTURE ON THERMAL STABILITY

The impact of using a thin AlGaAs layer as a carrier supplying layer in an InAlAs/InGaAs high electron mobility transistor structure (HEMT) on thermal stability has been investigated. The new structure exhibited no deterioration in its sheet carrier concentration after annealing for 15 min at 450 °C in nitrogen atmosphere, while in the conventional HEMT structure 20% deterioration was observed. The secondary ion mass spectroscopy analysis indicated that this excellent thermal stability originated from the absence of reaction between dopant and fluorine. By exposing the new and conventional HEMT structure in a fluorine atmosphere, it was obvious that the new structure had at least a five times higher tolerance to fluorine.