Sr. Bahl et Ja. Delalamo, ELIMINATION OF MESA-SIDEWALL GATE LEAKAGE IN INA1AS INGAAS HETEROSTRUCTURES BY SELECTIVE SIDEWALL RECESSING/, IEEE electron device letters, 13(4), 1992, pp. 195-197
Conventional mesa isolation in InAlAs/InGaAs HFET's results in the gat
e coming in contact with the exposed channel at the mesa sidewall, for
ming a parasitic gate-leakage path. We propose and successfully demons
trate a novel and simple method of recessing the channel edge into the
mesa sidewall using a succinic-acid-based selective etchant for InGaA
s over InAlAs. SEM photographs confirm the recessing of the channel al
ong the sidewall. Special heterostructure diodes, designed with varyin
g amounts of mesa-sidewall/gate-metal overlap, were fabricated with an
d without the sidewall isolation step. Electrical measurements confirm
the complete elimination of sidewall leakage on both diodes and HFET'
s.