Faculty Sponsor's Department(s):
With a wide band gap (4.8 eV) and a high projected breakdown field (8 MV/cm), β-phase Ga2O3 exhibits desirable optical and electrical properties for application in both solar blind UV photodetectors and power electronics. To achieve optimal Ga2O3 based device performance in these applications a highly doped (1020 atom/cm3) Ga2O3 thin film is required, specifically for tuning the band gap for UV optoelectronics and producing a high carrier mobility/low resistivity region directly under the contact pads in power transistors. To this end a series of highly Sn doped Ga2O3 thin films with varied Sn concentrations were deposited by radio frequency magnetron co-sputtering on c-plane sapphire substrates. The crystallinity, crystal phase, and morphology were determined by XDR, SEM and AFM, carrier concentration and mobility will be characterized by Hall measurements and the optical properties were determined by spectroscopic ellipsometry and UV-Vis. The band gap of the films shows a clear trend of decreasing band gap energy as a function of Sn content with the highest Sn concentration sample having a band gap energy of 4.6 eV. There is a clear shift to an amorphous phase when Sn sputtering power is more than 10% of Ga2O3 sputtering power. We anticipate that these films will have a high carrier concertation and mobility with low resistivity, which will be ascertained by Hall effect measurements. The initial results show that doping Ga2O3 thin films with Sn content below 10% Ga2O3 sputtering power produces thin films with high crystalline quality and desirable optical properties thereby demonstrating the viability of using magnetron co-sputtering to producing highly doped Ga2O3 thin films.