Growth and characterisation of high electron mobility transistors on 4H-SiC by ammonia molecular beam epitaxy

The growth of GaN/AlGaN high electron mobility transistor structures (HEMT) on 4H-SiC by ammonia molecular beam epitaxy (a-MBE) is reported. Structures were grown using a magnetron sputter epitaxy deposited AlN buffer layer prior to the MBE growth of a carbon-doped insulating GaN isolation layer, undoped GaN channel layer and AlGaN cap layer. No ex-situ or in-situ high temperature pre-treatment of the SiC substrate was used. The electrical characteristics of the layers was excellent with RT mobilities of >1100 cm2/Vs for a sheet carrier density of >1 ? 1013 cm?-?2. HEMTs fabricated from layers gave an ft and fmax of 36 and 80 GHz, respectively with a maximum saturated drain current of 450 mA/mm and transconductance of 160 mS/mm for a gate length of 0.3 mum.NRC publication: Ye