Room Temperature 2DEG Mobility Above 2350 cm2/V·s in AlGaN/GaN HEMT Grown on GaN Substrate

A high quality Al0.25Ga0.75N/GaN high electron mobility transistor (HEMT) structure was grown on a 2-inch GaN substrate by metalorganic chemical vapor deposition (MOCVD). In order to protect the stability of the GaN substrate, this paper proposes a two-stage heating method for surface stabilization. This method can effectively protect the GaN substrate during the heating treatment and is conducive to obtaining a smooth film surface and low dislocation density. Root-mean-square (RMS) roughness of the structure was as low as 0.12 nm over a 10 × 10 μm2 region. The dislocation density was approximately on the order of 105 cm−2. The HEMT structure exhibited a room temperature two-dimensional electron gas (2DEG) mobility up to 2396 cm2/V·s with a 2DEG density of 0.89 × 1013 cm−2. This is the highest mobility ever reported. This high 2DEG mobility is partly attributed to the smooth surface and good crystal quality.