Title :
Negative base current and impact ionization phenomena in AlGaAs/GaAs HBTs
Author :
Zanoni, Enrico ; Malik, Roger ; Pavan, Paolo ; Nagle, Julien ; Paccagnella, Alessandro ; Canali, Claudio
Author_Institution :
Dipartimento di Elettronica e Inf., Padova Univ., Italy
fDate :
5/1/1992 12:00:00 AM
Abstract :
Impact ionization phenomena in the collector region of AlGaAs/GaAs heterojunction bipolar transistors give rise to base current reduction and reversal. These phenomena can be characterized by extracting the M-1 coefficient, which can be evaluated by measuring base current changes. Measurements of M-1 are affected at low current densities by the presence of the collector-base junction reverse current I/sub CBO/. At high current densities, three effects contribute to lower the measured M-1 value: voltage drops due to collector (R/sub C/) and base (R/sub B/) parasitic resistances, device self-heating, and lowering of the base-collector junction electric field due to mobile carriers. By appropriately choosing the emitter current value, parasitic phenomena are avoided and the behavior of M-1 as a function of the collector-base voltage V/sub CB/ in AlGaAs/GaAs HBTs is accurately characterized.<>
Keywords :
III-V semiconductors; aluminium compounds; gallium arsenide; heterojunction bipolar transistors; impact ionisation; AlGaAs-GaAs; HBTs; M-1 coefficient; base current reduction; base-collector junction electric field; collector region; collector-base junction reverse current; collector-base voltage; device self-heating; emitter current value; heterojunction bipolar transistors; impact ionization phenomena; mobile carriers; negative base current; parasitic resistances; Charge carrier processes; Current density; Current measurement; Density measurement; Electrical resistance measurement; Gallium arsenide; Heterojunction bipolar transistors; Impact ionization; Irrigation; Voltage;
Journal_Title :
Electron Device Letters, IEEE
