High-speed performance of InP/In0.53Ga0.47As/InP double-heterojunction bipolar transistors

A theoretical comparison of In0.53Ga0.47As/InP and Al0.3Ga0.7As/GaAs heterojunction bipolar transistors has been undertaken in an effort to determine the relative merits of these material systems. The analysis uses a compact transistor model and considers devices with self-aligned geometries including both extrinsic and intrinsic parameters. The high electron mobility in the In0.53Ga0.47As base layer and high peak velocity of electrons in the collector depletion layer result in a current gain cutoff frequency in excess of 150 GHz for an InP/In0.53Ga0.47As transistor with base thickness of 0.1 μm. Calculations revealed, however, that maximum oscillation frequency is strongly dependent on the contact resistance of the p-type base layer, even for a self-aligned base transistor. A maximum oscillation frequency of 138 GHz is theoretically predicted for an InP/In0.53Ga0.47As transistor with base thickness of 0.06 μm, base doping of 1×1020 cm−3, a p-type contact resistance of 1.0×10−7 Ω cm2, a current density of 5×104 A/cm2, and a VCB of 5 V.