Title :
Dependence of DC current gain and f/sub max/ of AlInAs/GaInAs HBTs on base sheet resistance
Author :
Hafizi, Madjid ; Metzger, Robert A. ; Stanchina, William E.
Author_Institution :
Hughes Res. Labs., Malibu, CA, USA
fDate :
7/1/1993 12:00:00 AM
Abstract :
To investigate the effect of base sheet resistance on DC current gain and maximum frequency of oscillation (f/sub max/) values, AlInAs/GaInAs HBT wafers were grown with base doping levels in the range of 2*10/sup 19/ to 1.6*10/sup 20/ cm/sup -3/. To confine the p-dopant within a nominal base thickness of 0.05 mu m, the molecular beam epitaxial (MBE) growth was performed over a substrate temperature range of 430 degrees C to 280 degrees C. The resulting base sheet resistances of 11 wafers were in the range of 900 down to 141 Omega /sq. DC current gains of greater than 20 were obtained with a base sheet resistance of 250 Omega /sq, and the current gain dropped to five for a sheet resistance of 141 Omega /sq. The f/sub max/ did not scale with the square root of the base resistances as predicted by the classical expression.<>
Keywords :
III-V semiconductors; aluminium compounds; gallium arsenide; heterojunction bipolar transistors; indium compounds; molecular beam epitaxial growth; semiconductor growth; solid-state microwave devices; 0.05 micron; 110 to 130 GHz; 280 to 430 C; 72 to 106 GHz; AlInAs-GaInAs; DC current gain; HBT wafers; MBE growth; base doping levels; base sheet resistance; maximum oscillation frequency; molecular beam epitaxial growth; nominal base thickness; semiconductor; Doping; Frequency; Heterojunction bipolar transistors; Molecular beam epitaxial growth; Substrates; Temperature distribution;
Journal_Title :
Electron Device Letters, IEEE
