Title :
Parasitic energy barriers in SiGe HBTs
Author :
Slotboom, Jan W. ; Streutker, G. ; Pruijmboom, A. ; Gravesteijn, D.J.
Author_Institution :
Philips Res. Lab., Eindhoven, Netherlands
Abstract :
Parasitic energy barriers can easily be introduced during processing. Measurements and calculations of experimental n-p-n HBTs (heterojunction bipolar transistors) are presented, showing that a parasitic conduction-band barrier at the base-collector junction reduces the collector current and the cutoff frequency. A simple analytical model explains the f/sub T/ degradation, caused by the reduction of the collector current and a pileup of minority carriers in the base. With the model the effective height and width of the barrier can also be derived from the measured collector current enhancement factor I/sub C/(SiGe)/I/sub C/(Si).<>
Keywords :
Ge-Si alloys; conduction bands; heterojunction bipolar transistors; minority carriers; secondary ion mass spectra; semiconductor device models; semiconductor materials; SIMS profiles; SiGe-Si; analytical model; base-collector junction; collector current; collector current enhancement factor; cutoff frequency; minority carrier pileup; n-p-n HBTs; parasitic conduction-band barrier; parasitic energy barriers; Analytical models; Current measurement; Cutoff frequency; Degradation; Electron mobility; Energy barrier; Germanium silicon alloys; Heterojunction bipolar transistors; Photonic band gap; Silicon germanium;
Journal_Title :
Electron Device Letters, IEEE
