Enhancement and depletion-mode phemt device having two ingap etch-stop layers

摘要

A depletion/enhancement PHEMT device structure is provided. The structure comprises: (a) a semiconductor substrate; (b) a buffer region comprising one or more semiconductor buffer layers over the substrate; (c) a III-V semiconductor channel layer over the buffer region; (d) an electron donor layer over the channel layer; (e) a GaAs or AlGaAs first schottky layer over the electron donor layer; (f) a first InGaP layer over the first schottky layer; (g) a GaAs or AlGaAs second schottky layer over the first InGaP layer; (h) a second InGaP layer over the second schottky layer; (i) a doped GaAs contact layer over the second InGaP layer; (j) an isolation structure extending from an upper surface of the contact layer at least to the buffer region, the isolation structure defining a first active region and a second active region; (k) an enhancement ohmic source contact and an enhancement ohmic drain contact disposed on the doped GaAs contact layer within the first active region; (l) an enhancement gate recess extending from an upper surface of the contact layer and through the first InGaP layer within the first active region; (m) an enhancement gate contact disposed over the first schottky layer within the enhancement gate recess; (n) a depletion ohmic source contact and a depletion ohmic drain contact disposed on the doped GaAs contact layer within the second active region; (o) a depletion gate recess extending from an upper surface of the contact layer and through the second InGaP layer within the second active region; and (p) a depletion gate contact disposed over the second schottky layer within the depletion gate recess.