Low temperature homoepitaxy of (010) β-Ga_2O_3 by metalorganic vapor phase epitaxy: Expanding the growth window

摘要

In this work, we report on the growth of high-mobility β-Ga_2O_3 homoepitaxial thin films grown at a temperature much lower than the conventional growth temperature window for metalorganic vapor phase epitaxy. Low-temperature β-Ga_2O_3 thin films grown at 600 °C on Fe-doped (010) bulk substrates exhibit remarkable crystalline quality, which is evident from the measured room temperature Hall mobility of 186 cm~2/V s for the unintentionally doped films. N-type doping is achieved by using Si as a dopant, and a controllable doping in the range of 2 × 10~(16)-2 × 10~(19)cm~(-3) is studied. Si incorporation and activation is studied by comparing the silicon concentration from secondary ion mass spectroscopy and the electron concentration from temperature-dependent Hall measurements. The films exhibit high purity (low C and H concentrations) with a very low concentration of compensating acceptors (2 × 10~(15)cm~(-3)) even at this growth temperature. Additionally, an abrupt doping profile with a forward decay of ～ 5nm/dec (10 times improvement compared to what is observed for thin films grown at 810 °C) is demonstrated by growing at a lower temperature.