DocumentCode :
2538683
Title :
HBT on LEO GaN
Author :
McCarthy, L. ; Smorchkova, Y. ; Fini, P. ; Xing, H. ; Rodwell, M. ; Speck, J. ; DenBaars, S. ; Mishra, U.
Author_Institution :
Dept. of Electr. & Comput. Eng., California Univ., Santa Barbara, CA, USA
fYear :
2000
fDate :
19-21 June 2000
Firstpage :
85
Lastpage :
86
Abstract :
Dramatic progress in GaN electronics has led to increased interest in bipolar transistors. Although there have been reports of GaN bipolars from several groups, the development of the GaN bipolar transistor is still in its fundamental stages. In the case of GaN, the usual correlation between common base, Gummel, and common emitter characteristics does not exist due to significant collector-emitter leakage, leaving only the common emitter characteristic as a reliable measure of DC device performance. We identify the source of this leakage as threading dislocations and clarify the effect of this leakage on the transistor DC characteristics. Furthermore, we conclude from various growth structures and methods of device fabrication that the electron lifetime in the neutral base is currently the limiting factor in GaN NPN transistor performance. Typical GaN material has high threading dislocation densities, 10/sup 7/-10/sup 9/ cm/sup -2/, due to lattice mismatch with the substrate, typically sapphire or SiC. To study the effects of threading dislocations on GaN bipolar transistors, we have fabricated devices on material grown using the lateral epitaxial overgrowth technique, LEO. To the authors´ knowledge, this is the first demonstration of GaN bipolar transistors grown on nondislocated material. The LEO substrate allows us to compare devices grown on material with a negligible dislocation density with those grown on a standard template.
Keywords :
III-V semiconductors; MOCVD; carrier lifetime; dislocation density; gallium compounds; heterojunction bipolar transistors; leakage currents; semiconductor growth; vapour phase epitaxial growth; wide band gap semiconductors; Al/sub 2/O/sub 3/; DC device performance; GaN NPN transistor performance; GaN bipolar transistors; GaN electronics; GaN-Al/sub 2/O/sub 3/; Gummel characteristics; LEO GaN HBT; LEO substrate; MOCVD; bipolar transistors; collector-emitter leakage; common base characteristics; common emitter characteristic; common emitter characteristics; device fabrication; dislocation density; growth methods; growth structures; lateral epitaxial overgrowth technique; lattice mismatch; neutral base electron lifetime; nondislocated substrate material; threading dislocation density; threading dislocations; transistor DC characteristics; Bipolar transistors; Electrons; Fabrication; Gallium nitride; Heterojunction bipolar transistors; Lattices; Low earth orbit satellites; MOCVD; Molecular beam epitaxial growth; Substrates;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Device Research Conference, 2000. Conference Digest. 58th DRC
Conference_Location :
Denver, CO, USA
Print_ISBN :
0-7803-6472-4
Type :
conf
DOI :
10.1109/DRC.2000.877101
Filename :
877101
Link To Document :
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