The results of use of STE3N MBE System for growth of GaN nanoheterostructures by both types of MBE (using plasma activation of nitrogen and ammonia) are presented. It is shown that the use of high-temperature AlN/AlGaN buffer layers grown using ammonia at extremely high temperatures (up to 1150??C) allows improving drastically the structural quality of the GaN layers and reducing the dislocation density down to 9??108???1??109 cm???2. On the other hand, unlike the ammonia MBE, which is difficult to use at T <5000C (because of low decomposition efficiency of ammonia), PA-MBE is very effective at low temperatures, for example for growth of InAlN layers lattice-matched to GaN. The results of the growth of high quality GaN/InAlN heterostructures using both PA-MBE and NH3-MBE (at extremely high ammonia flux) are shown. The use of SemiTEq equipment in Svetlana-Rost JSC for high power microwave FETs based on GaN is demonstrated.