Ultrafast growth rate and high mobility In2O3 films grown on c-sapphire via low pressure chemical vapor deposition

Abstract

In this study, the growth of unintentionally doped semiconductor indium oxide with ultrafast growth rates on c-plane sapphire by low pressure chemical vapor deposition (LPCVD) was demonstrated. The effect of key growth parameters, such as oxygen flow rate and distance between the substrate to the indium source, on the growth rate, crystalline quality, surface morphology, as well as carrier transport properties were studied. The growth rate is highly dependent on the oxygen flow rate and the distance between the indium source and the substrate: (i) the growth rate reaches 113 μm/h with an oxygen flow rate of 75 sccm under the investigated growth condition; and (ii) it decreases exponentially with the increase of distance between the indium source and the substrate. X-ray diffraction characterization of the as-grown films indicates that the increase of oxygen flow rate leads to the suppression of (100) facet formation, significantly influencing the film morphology. The LPCVD growth conditions also determine the background doping and carrier mobility. With an oxygen flow rate of 75 sccm, a high electron mobility of 126 cm2 V−1 s−1 with a bulk concentration of 3.9 × 1017 cm−3 was obtained. Results from this work provide guidance on LPCVD growth of In2O3 with targeted growth rate, surface morphology, carrier concentration, and mobility.