Summary: | A comprehensive, one-dimensional, analytical model of the graded-base
AlGaAs/GaAs heterojunction bipolar transistor is presented, and used to examine the
influence of optical injection on the DC and high-frequency performance of a device with a
conventional pyramidal structure. Absorption is limited to the base and collector regions
because of the window effect of the wider bandgap emitter. Grading is considered by
varying the A l mole fraction x linearly across the base to a value of zero at the base-collector
boundary. Recombination in the space-charge and neutral regions of the device
is modeled by considering Shockley-Read-Hall, Auger and radiative processes.
Experimental devices were obtained from the Communications Research Centre, Ottawa
and packaged by the author at the Alberta Microelectronics Centre and the
Telecommunications Research Laboratory, Edmonton. The packaged devices were tested
to evaluate the DC and high-frequency performances. Comparisons between predictions
of the model and experimental data from a packaged device are presented. Optical
injection is observed to improve the DC and high-frequency characteristics of the device. === Applied Science, Faculty of === Electrical and Computer Engineering, Department of === Graduate
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