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IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 51, NO. 10, OCTOBER 2004 1545 Impact of Compositionally Graded Base Regions
 

Summary: IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 51, NO. 10, OCTOBER 2004 1545
Impact of Compositionally Graded Base Regions
on the DC and RF Properties of Reduced Turn-On
Voltage InGaP­GaInAsN DHBTs
Kevin S. Stevens, Member, IEEE, Rebecca J. Welty, Member, IEEE, Roger E. Welser, Barbara E. Landini,
Peter M. Asbeck, Fellow, IEEE, Shih-Chieh Hung, Wen-Pin Lu, and Shun-Ching Feng
Abstract--Built-in drift fields are employed to enhance the
performance of GaAs-based heterojunction bipolar transistors
(HBTs) with reduced turn-on voltage. Specifically, we explore in
detail the dc and RF device property improvements enabled by
using compositionally graded GaInAsN base layers. Experimental
results are compared to predictions of the standard drift-diffusion
base transport model employing a finite exit velocity. In large area
devices, graded base samples with built-in fields of 7 kV/cm (i.e.
40 meV over 500 A) typically have a dc current gain 1.8 larger
than constant base composition samples. In small area devices,
the peak cut-off frequency is typically 10%­15% higher than
constant composition samples. These results are shown to agree
reasonably well with predictions, thereby demonstrating that
analytical drift-diffusion based models can be extended to HBTs

  

Source: Asbeck, Peter M. - Department of Electrical and Computer Engineering, University of California at San Diego

 

Collections: Engineering