An asymmetric insulated-gate field-effect transistor is configured in an asymmetric lightly doped drain structure that alleviates hot-carrier effects and enables the source characteristics to be decoupled from the drain characteristics. The transistor has a multi-part channel formed with an output portion, which adjoins the drain zone, and a more heavily doped input portion, which adjoins the source zone. The drain zone contains a main portion and more lightly doped extension that meets the output channel portion. The drain extension extends at least as far below the upper semiconductor surface as the main drain portion so as to help reduce hot-carrier effects. The input channel portion is situated in a threshold body zone whose doping determines the threshold voltage. Importantly, the provision of a lightly doped source extension is avoided so that improving the drain characteristics does not harm the source characteristics, and vice versa. In fabricating complementary versions of the transistor, the threshold body zone of one transistor can be formed at the same time as the drain extension of a complementary transistor, and vice versa.