In this work a systematic methodology for the direct growth of GaN after the AlN nucleation layer on 6-inch silicon substrates for high electron mobility transistors (HEMT) applications is demonstrated. The buffer-less design enables crucial growth-stress modulation to prevent epilayer cracking, has similar threading dislocation densities to samples with buffer and a significantly lower GaN-to-substrate thermal resistance. As-grown AlGaN/AlN/GaN HEMT structures on this template exhibit a high-quality 2D electron gas (2DEG) with a room-temperature Hall-effect mobility above 2000 cm2/(V·s). A low-temperature magnetoresistance measurement of the 2DEG shows Shubnikov-de-Haas oscillations, a quantum lifetime > 0.180 ps, as well as tell-tale signatures of spin-splitting.

Description of the dataset:

File: “Figure 1.zip” contains stress and structural characterisation datasets of GaN/AlN/Si heterostructures

• Fig. 1b: stress-thickness curves and mean stress curves with thickness measured during the GaN growth at 200 Torr, 125 Torr, 75Torr, 37.5Torr, and 18 Torr.
• Fig. 1c: Final Mean-stresses after 800 nm GaN growth, averaged from multiple growth runs.
• Fig. 1d: Wafer-bows at room-temperature for samples grown under different pressures
• Fig. 1e: X-ray diffraction (XRD) reciprocal space map of the20-25 AlN reflection.
• Fig. 1f: XRD ω-2Θ scan data showing peaks from the epilayer and substrate
• Fig. 1g: XRD Φ-scans of the 20-21 GaN 400 Si reflections.

File: “Figure 2.zip” contains the following dataset

• Fig. 2a: Reflectance transients measured during 800 nm GaN growths at 18 Torr and 200 Torr.

File: “Figure 3.zip” contains structural characterization data of GaN/AlN/Si heterostructures.

• Fig. 3a: ω-Full width at half maximum values (ω-FWHM) of the XRD 20-21 and 0002 reflections of GaN layers grown at different growth pressures.
• Fig. 3b: Variation of the total and individual dislocation density at the surface of the GaN layers grown at different pressures.

File: “Figure 4.zip” contains the thermal characterisation data of GaN/AlN/Si heterostructures

• Fig. 4b: Normalised eperimental and modeled thermoreflectance data for the sample for which the GaN layer was grown at 75 Torr
• Fig. 4c: Sensitivity analysis with respect to the variation in thickness and the effective thermal conductivity of AlN

File: “Figure 5.zip” contains data on the interfacial confinement and room-temperature (RT) transport properties of the 2DEG in GaN/AlN/Si heterostructures

• Fig. 5a: Experimental and simulated XRD ω-2Θ data of the symmetric 004 reflection
• Fig. 5b: Simulated conduction band edge and electron concentration across the sample structure showing confinement of the electrons on the GaN side of the interface.
• Fig. 5c: Hall-effect measured variation in 2DEG electron density and mobility with barrier composition for designs without and with AlN spacer.

File: “Figure 6.zip” contains data on Quantum Hall signatures in the AlGaN/AlN/GaN 2DEG at low temperatures

• Fig. 6a: Change in longitudinal magnetoresistance (Rxx) with increasing magnetic field, B, at 1.8 K.
• Fig. 6b: Second derivative of the raw magnetoresistance data (from file Fig. 6a) shows the changing Shubnikov-de-Haas (SdH) amplitudes with magnetic fields.
• Fig. 6c: Measured and fitted temperature dependence data of the normalized magnetoresistance peak at a constant magnetic field of 7.05 T.
• Fig. 6d: Experimental and fitted Dingle plot data for the oscillation amplitude peaks from ≈ 5.5 T to ≈ 13 T, considering an effective mass of m* = 0.210 m0 (obtained from dataset Fig. 6c).