Highly uniform AlGaN/GaN HEMT films grown on 200-mm silicon substrates by plasma molecular beam epitaxy

Highly uniform AlGaN/GaN HEMT films with good electron transport properties have been grown on 200-mm silicon substrates by plasma molecular beam epitaxy. X-ray diffraction measurements indicate an AlGaN compositional and thickness variation of ±1% across the wafer, and a 29 point resistance map of a HEMT yielded a sheet resistance of 451 Ω/sq ± 1.1%. The electron mobility for seven measurements taken across the diameter of the wafer was 1555 cm2/Vs ± 1%. The mobility obtained on 200-mm silicon is within 10% of the mobility obtained for GaN HEMTs grown on 100-mm SiC substrates, which have a much smaller lattice mismatch with GaN. The uniform films were obtained at GaN growth rates comparable to 100-mm growth and a chamber pressure well within the free molecular flow regime.