Research on nano-scale AlN nucleation layer growth and GaN HEMT characteristics based on MOCVD technology

•By in-situ high-temperature etching of the substrate, a 5.8 nm-thick AlN nucleation layer was grown on a 100 mm 4H-SiC substrate in a low-pressure MOCVD.•Based on the 5.8 nm thick AlN nucleation layer, the dislocation density of the GaN epitaxial layer prepared was 4.5 × 108cm−2, and the electron mobility of the 2DEG reached 2200 cm2/V·s.•The thermal resistance of the AlN interface was reduced by 48%, reaching 5.53 × 10−9 m2K/W, when the AlN nucleation layer thickness was reduced by 80% to 11.6 nm. The AlN nucleation layers of different thicknesses were grown on a 100 mm 4H-SiC substrate in a low-pressure MOCVD. By using in-situ high-temperature etching of the substrate steps, the AlN nucleation layer could achieve layered growth as soon as possible, and finally achieve 11.6 nm. The complete AlN film was prepared, and the surface morphology and interface quality of AlN were analyzed with atomic force microscope and transmission electron microscope. A 1.8 μm thick GaN HEMT epitaxial material was prepared based on the ultra-thin AlN nucleation layer. The (002) and (102) plane rocking curves of GaN had a FWHM of 138arcsec and 231arcsec, and the electrons mobility of the heterojunction two-dimensional electron gas reached 2200 cm2/V·s. The AlN interface thermal resistance measured by the high-precision 3ω method was reduced to 5.53 × 10−9 m2K/W.