Fabrication and characterization of capless In0.52AI0.48As/In0.53Ga0.47As HEMTs

Capless high electron mobility transistors (HEMTs) were fabricated and their DC and RF performances were characterized. Capless HEMTs did not have highly doped InGaAs cap layer so that gate recess process was not required in the fabrication of capless HEMTs. The electrical performances of the capless HEMTs were compared with those of conventional HEMTs with highly doped InGaAs cap layer. A typical 0.2 mu m capless HEMT exhibited a maximum transconductance of 805 mS/mm, a threshold voltage of -0.5 V, and a unity current gain cut-off frequency (f(T)) of 137 GHz. Capless HEMTs exhibited improved device uniformity compared with conventional HEMTs fabricated by wet gate recess technology.