Enhanced AlScN/GaN Heterostructures Grown with a Novel Precursor by Metal-Organic Chemical Vapor Deposition

Growth of AlScN high-electron-mobility transistor (HEMT) structures by metal-organic chemical vapor deposition (MOCVD) is challenging due to the low vapor pressure of the conventionally used precursor tris-cyclopentadienyl-scandium (Cp3Sc). It is shown that the electrical and structural characteristics of the AlScN/GaN heterostructure improve significantly by using bis-methylcyclopentadienyl-scandiumchloride ((MCp)2ScCl), which has a higher vapor pressure and allows for an increased molar flow and thus higher growth rate (GR). AlScN/GaN HEMT heterostructures with superior electrical characteristics deposited at different barrier growth temperatures are presented. The sheet resistance R(sh) of 172 Ω sq(-1) obtained at 900 °C barrier growth temperature is among the lowest reported so far for AlScN/GaN HEMT structures. The sheet charge carrier density n(s) is 3.23 x 10(13) cm(-2) and the electron mobility μ is 1124 cm(2) Vs(-1).