InGaAs/InP DHBTs in a Dry-Etched Refractory Metal Emitter Process Demonstrating Simultaneous $f_{\tau}/f_{\max} \sim \hbox{430/800}\ \hbox{GHz}$

Abstract-We report an InPZIn
_0.53
Ga
_0.47
As/InP double heterojunction bipolar transistor (DHBT) demonstrating simultaneous 430-GHz f
_τ
and 800-GHz f
_max
. The devices were fabricated using a triple mesa process with dry-etched refractory metals for emitter contact formation. The devices incorporate a 30-nm-thick InP emitter semiconductor which enables a wet-etch emitter process demonstrating 270-nm-wide emitter-base junctions. At peak RF performance, the device is operating at 30 mW/μm
²
with J
_c
= 18.4 mA/μm
²
and V
_ce
= 1.64 V. The devices show a peak DC common-emitter current gain (β) ~ 20 and V
_BR,CEO
= 2.5 V.