Cubic GaN/AlGaN HEMTs on 3C-SiC Substrate for Normally-Off Operation

Masayuki ABE
Hiroyuki NAGASAWA
Stefan POTTHAST
Jara FERNANDEZ
Jorg SCHORMANN
Donat Josef AS
Klaus LISCHKA

Publication
IEICE TRANSACTIONS on Electronics   Vol.E89-C    No.7    pp.1057-1063
Publication Date: 2006/07/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.7.1057
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Heterostructure Microelectronics with TWHM2005)
Category: GaN-Based Devices
Keyword: 
cubic GaN,  GaN/AlGaN HEMT,  piezo,  spontaneous,  polarization,  blocking voltage,  

Full Text: PDF(676KB)>>
Buy this Article


Summary: 
Phase pure cubic (c-) GaN/AlGaN heterostructures on 3C-SiC free standing (001) substrates have successfully been developed. Almost complete (100%) phase pure c-GaN films are achieved with 2-nm surface roughness on 3C-SiC substrate and stoichiometric growth conditions. The polarization effect in c-GaN/AlGaN has been evaluated, based on measuring the transition energy of GaN/AlGaN quantum wells (QWs). It is demonstrated that the polarization electric fields are negligible small in c-GaN/AlGaN/3C-SiC compared with those of hexagonal (h-)GaN/AlGaN, 710 kV/cm for Al content x of 0.15, and 1.4 MV/cm for x of 0.25. A sheet carrier concentration of c-GaN/AlGaN heterojunction interface is estimated to 1.61012 cm-2, one order of magnitude smaller than that of h-GaN/AlGaN. The band diagrams of c-GaN/AlGaN HEMTs have been simulated to demonstrate the normally-off mode operation. The blocking voltage capability of GaN films was demonstrated with C-V measurement of Schottky diode test vehicle, and extrapolated higher than 600 V in c-GaN films at a doping level below 51015 cm-3, to show the possibility for high power electronics applications.