Heterojunction Bipolar Transistor Having Reduced Extrinsic Base Resistance
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
This article describes a heterojunction bipolar transistor having an extrinsic base region made of a low resistance metallic compound. The structure effectively reduces extrinsic base resistance and collector- base capacitance and provides improved frequency characteristics. The metallic compound extrinsic base region can be utilized as a Schottky contact to form a Schottky clamp diode connected between the base and the collector. Fig. 1 shows the present heterojunction bipolar transistor including a region of n - GaAlAs (emitter E), a region of p - GaAs (base B), a region of n - GaAs (collector C), and a region of n+ - GaAs (subcollector SC). The extrinsic base region is made of a low resistance metallic compound, such as a Pt/GaAs compound.