Physical Properties of AlGaN/GaN Heterostructures Grown on Vicinal Substrates

Grenko, J. A.; Reynolds, C. L.; Barlage, Douglas W.; Johnson, Mark A.; Lappi, Simon E.; Ebert, Chris; Preble, E. A.; Paskova, T.; Evans, K. R.

doi:10.1007/s11664-010-1153-0

Cited by 8 publications

(2 citation statements)

References 69 publications

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“…3 However, very few reports on the effects of offcut of bulk GaN substrates on subsequent epitaxy exist in the literature, and these are primarily concerned with the growth of InGaN as compared to AlGaN. 4,5,6 This work aims to elucidate the effect of the surface offcut on the compositional and electrical performance of AlGaN/GaN heterostructures on bulk GaN substrates.…”

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confidence: 99%

Effect of substrate offcut on AlGaN/GaN HFET structures on bulk GaN substrates

et al. 2011

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Bulk GaN substrates promise to bring the full potential of nitride-based devices to bear since they offer a low thermal and lattice mismatched alternative to foreign substrates for epitaxial growth. However, due to the high cost and low availability of bulk GaN substrates, effects such as surface misorientation (offcut), surface polishing, and preparation of such substrates on subsequent epitaxy are still not well understood. As such, AlGaN/GaN heterostructures with nominal Al compositions of 25% were grown by MOCVD on semi-insulating bulk GaN substrates with offcuts ranging from 0.05 to 1.95° in the m-direction ( ) 0 1 10 to attempt to determine the optimal offcut for bulk GaN substrates for AlGaN-based HFET devices. X-ray diffraction (XRD) studies indicate that the Al composition does not vary with offcut, however reciprocal space mapping shows evidence of strain relaxation of the AlGaN in samples grown on substrates with offcut >1.1°. Additionally, we observed a minimum in sheet resistance of the 2DEGs for substrates with offcuts near 0.5°, arising from higher mobilities in these samples. Evidence of an optimal substrate misorientation is important for AlGaN-based devices grown on bulk GaN substrates.

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Section: Introductionmentioning

confidence: 99%

Effect of substrate offcut on AlGaN/GaN HFET structures on bulk GaN substrates

et al. 2011

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“…al reported that UV photoenhanced chemical etching of the GaN substrates reduced the concentration of Si at the interface, but did not completely eliminate it [3]. As a result, impurities including Fe [3,4], C [2] and Mg [5] have been added to compensate the remaining Si donors.…”

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Dual temperature process for reduction in regrowth interfacial charge in AlGaN/GaN HEMTs grown on GaN substrates

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et al. 2011

Phys. Status Solidi C

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The effects of growth temperature and Mg compensation doping on the structural and electrical properties of AlGaN/AlN/GaN high electron mobility transistor (HEMTs) structures grown on low threading dislocation density bulk GaN substrates by metalorganic chemical vapor deposition were investigated. The background electron concentration in the regrown GaN was found to decrease from 1.5x1018 cm‐3 to 2x1016 cm‐3 as the growth temperature was reduced from 1100 °C to 950 °C. A dual temperature process was then employed for growth of the GaN base layer and AlGaN/AlN/GaN top heterostructure in the HEMT along with Mg doping of the GaN base to compensate residual Si donors at the regrown interface. Using this approach, AlGaN/AlN/GaN HEMTs were produced that had a sheet carrier density as high as 1.1x1013 cm‐3 with a room temperature mobility of 1600 cm2/Vs. The incorporation of a thin AlN layer at the regrown interface was found to reduce the sheet carrier density of the overall structure (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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