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Summary: International Journal of High Speed Electronics and Systems World Scientific
Vol. 14, No. 3 (2004) 825-830 p www.worldscientific.om
( World Scientific Publishing Company
ANALYSIS OF HIGH DC CURRENT GAIN STRUCTURES FOR
GaN/InGaN/GaN HBTs
JAMES C. LI, DAVID M. KEOGH, SOUROBH RAYCHAUDHURI,
ADAM CONWAY, DONGJIANG QIAO, AND PETER M. ASBECK
Electrical and Computer EngineeringDepartment, University ofCalifornia - San Deigo, 9500
Gilman Drive, La Jolla, CA 92093, USA
AlGaN/GaN HBTs with DC current gains in excess of 10 have been demonstrated; however,
Makimoto et al have recently obtained a DC current gain value exceeding 2000 for a
GaN/InGaN/GaN triple mesa DHBT.' The expeimental demonstration of a GaN-based HBT with
such extraordinary DC cunrent gain has motivated the search for new device structures conducive to
high DC current gain. Simulations in this work indicate that high DC current gain is difficult to
achieve with a uniform, defect-free base layer. We also simulate the electrical characteristics of a
new class of DHBT where the base layer is non-uniform By non-unifomly thinning or perforating
the base, the majority of the base would remain thick to minimize the negative impact to base
resistance. However, snall thinned regions achieve extremely high DC current gain, which can be
used to significantly increase the overall DC current gain. This device structure could naturally occur
when 'V' defects form or Indium is non-uniformly distributed during the base layer growth. The
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