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Towards low-trapping GaN-on-silicon material system for 1200 V applications
Archive ouverte : Communication dans un congrès
Edité par HAL CCSD
International audience. This paper presents an assessment of a GaN-on-silicon buffer structure from the epi-wafer providerALLOS Semiconductors GmbH targeting 1200 V power applications. Epiwafers with 150 mmdiameter were grown by MOCVD on Si (111) substrates. Total GaN thickness is 7.1 µm withseveral interlayers for strain management. Owing to ALLOS’ GaN-on-Si growth technologies,high crystal quality of GaN is obtained, with XRD FWHM of (002) and (102) being 395 and 423arcsec, respectively. Because of the thick and excellent crystal quality of GaN buffer, low leakagecurrent and state-of-the-art vertical breakdown voltage above 1400 V was achieved at roomtemperature. Furthermore, it can be pointed out that despite the absence of carbon doping into thebuffer layers, no evidence of punch-through effects has been noticed, which is reflected by anexcellent electron confinement in the DC characteristics of test transistors. In order to clarify theadvantage of this undoped GaN heterostructure, the properties of the new buffer are discussed interms of trapping phenomena using various techniques such as; substrate ramp and back-gatingtransient measurements. Both substrate ramp and back-gating results indicate that the traps arenegligible with the substrate voltage down to -1 kV. Some traps are activated by further decreasingthe substrate voltage down to -1.2 kV which implies the charge injection in the buffer at higherelectric field. This work shows that properly engineered carbon-free GaN-on-siliconheterostructures can not only provide outstanding vertical breakdown voltage with an excellentelectron confinement addressing 1200 V applications but could also generate low trapping effectsbeyond 1 kV in a near future
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