Double-heterojunction bipolar transistor having high cut-off frequency is based on ternary III-V semiconductor materials

摘要

Double-heterojunction bipolar transistor includes an emitter of wide forbidden band III-V material, a base of narrow forbidden band III-V material, and a collector of InAs1-yPy. The base material is selected such that its conduction band is at a higher energy than that of collector material, and its unit cell parameter is the same as that of collector material. Preferred Features: The base material is Ga1-xInxAs, where x - 60%, or GaIn1-zSbz, where z = 50-70%. The emitter material is InAs1-yPy, or Al1-xInxAs, (Al, Ga)1-xInxAs or (Al, Ga)As1-zSbz having the same unit cell parameter as that of collector material. The transistor includes a substrate of InP or GaAs. The base material has p-doped regions doped with both beryllium and carbon. Beryllium dopant is localized in the central region of the base remote from the collector and emitter, while carbon dopant is localized in the respective connection regions of the collector and emitter. The level of doping with carbon is less than that of beryllium, and the thickness of regions doped with carbon is tens of nanometers. Zinc can replace beryllium as dopant. One of the carbon-doped regions comprises a material having unit cell parameter different from that of the central region of the base. This difference in unit cell parameter is selected such that the carbon-doped region is under elastic stress. In particular, the carbon-doped region connected to the emitter is under tensile elastic stress or compressive elastic stress with respect to the base. The composition of the materials under stress and more especially the composition of the base material vary gradually.