| abstract |
A ED-HEMT structure includes a buffer layer ( 4 ) including a doped layer ( 18 ), a channel layer ( 6 ), a barrier layer ( 8 ), and a second doped layer ( 20 ). An enhancement mode HEMT gate ( 12 ) is formed in a via extending through the second doped layer ( 20 ) and a depletion mode HEMT structure is formed over the second doped layer ( 20 ). The layer sequence allows the formation of both enhancement and depletion mode HEMTs in the same structure with good properties. |