Title :
Polycrystal isolation of InGaP/GaAs HBTs to reduce collector capacitance
Author :
Mochizuki, K. ; Ouchi, K. ; Hirata, Kazufumi ; Tanoue, T. ; Oka, T. ; Masuda, H.
Author_Institution :
Central Res. Lab., Hitachi Ltd., Tokyo, Japan
Abstract :
InGaP/GaAs heterojunction bipolar transistors (HBTs) with polycrystalline GaAs buried under the base electrode have been fabricated using low-temperature gas-source molecular beam epitaxy on SiO2-patterned substrates. A cutoff frequency of 120 GHz and a maximum oscillation frequency of 230 GHz were obtained for three parallel 0.7×8.5 μm HBTs. Compared to HBTs without the polycrystal, the collector capacitance was reduced by 28% and the maximum stable gain was improved by 1.2 dB due to complete carrier depletion in the polycrystal under the base electrode. These results show the high potential of the proposed HBTs for high-speed digital and broadband-amplifier applications.
Keywords :
III-V semiconductors; buried layers; capacitance; chemical beam epitaxial growth; gallium arsenide; gallium compounds; heterojunction bipolar transistors; indium compounds; isolation technology; millimetre wave bipolar transistors; semiconductor growth; 0.7 mum; 120 GHz; 230 GHz; 8.5 mum; GaAs; InGaP-GaAs; InGaP/GaAs HBTs; SiO/sub 2/-GaAs; SiO/sub 2/-patterned substrates; base electrode; broadband-amplifier applications; buried polycrystalline GaAs; collector capacitance reduction; complete carrier depletion; cutoff frequency; high-speed digital applications; low-temperature gas-source molecular beam epitaxy; maximum oscillation frequency; maximum stable gain; polycrystal isolation; Bipolar transistors; Capacitance; Cutoff frequency; Doping; Electrodes; Gallium arsenide; Gold; Heterojunction bipolar transistors; Molecular beam epitaxial growth; Substrates;
Journal_Title :
Electron Device Letters, IEEE
