Title :
Novel HBT structure for high f/sub t/ at low current density
Author :
Chang, C.E. ; Asbeck, P.M. ; Tran, L.T. ; Streit, D.C. ; Oki, A.K.
Author_Institution :
California Univ., San Diego, La Jolla, CA, USA
Abstract :
Through modifications of the epitaxial structure of a GaAs/AlGaAs HBT, the junction capacitance (C/sub be/) and recombination rate in the base-emitter junction region have been substantially reduced. The modified structure leads to both higher f/sub t/ and higher /spl beta/ at low current densities (10/sup 2spl les/J/sub cspl les/10/sup 4/ A/cm/sup 2/). The modifications include a lightly doped emitter (LDE) and a strategically placed /spl delta/-doping layer. Device simulations were used to optimize the LDE length and location of the /spl delta/-doping. The experimental results of a fabricated device with a 1370 /spl Aring/ LDE+/spl delta/-doping yielded a 3.3x reduction in C/sub be/, a 2.7x increase in f/sub t/, and a 2x increase in /spl beta/ over the baseline device at low J/sub c/ (J/sub cspl les/10/sup 3/ A/cm/sup 2/).<>
Keywords :
III-V semiconductors; aluminium compounds; doping profiles; electron-hole recombination; gallium arsenide; heterojunction bipolar transistors; semiconductor device models; semiconductor doping; semiconductor epitaxial layers; /spl delta/-doping layer; 1370 angstrom; GaAs-AlGaAs; GaAs/AlGaAs; HBT structure; base-emitter junction region; current density; current gain; device simulations; epitaxial structure; junction capacitance; lightly doped emitter; recombination rate; Charge carrier processes; Computational modeling; Computer simulation; Current density; Degradation; Design optimization; Electron emission; Heterojunction bipolar transistors; Spontaneous emission; Thyristors;
Conference_Titel :
Electron Devices Meeting, 1993. IEDM '93. Technical Digest., International
Conference_Location :
Washington, DC, USA
Print_ISBN :
0-7803-1450-6
DOI :
10.1109/IEDM.1993.347279
