Effect of Growth Conditions on the Performance of Vertically Conducting β-Ga2O3 Diodes on 4H-SiC Substrate

We present the results of homojunction beta-gallium oxide (β-Ga2O3) vertically conducting diodes grown by metal-organic chemical vapor deposition (MOCVD). The epitaxial layers of β-Ga2O3 were of thickness ~ 0.5 um and were grown on n-doped 4-H silicon carbide (4H-SiC) substrate. To realize a diode structure, the initial growth layer on the substrate was doped with silicon with 5x10¹⁷ cm^-3, then ~ 0.25 um layer was kept undoped. Three different samples were grown by changing the growth conditions; the sample one was grown by the traditional method by providing the continuous flow of growth precursors for gallium, oxygen, and silicon; in sample two, silicon was delta-doped in the doped part of the structure, and the sample three, the doped structure of the device was co-delta doped with silicon and indium. All other parameters, such as chamber pressure, growth temperature, and total gas flow rate, were kept constant. The samples were characterized by x-ray diffraction (XRD), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS) prior to the processing. All three samples were processed to vertical conducting diodes of a diameter of 100 μm. The sample’s current-voltage (I-V) characteristics were measured and compared with each other and correlated with the growth process. All samples show significantly higher turn-on voltage due to high series resistance. Delta-doped samples showed lower turn-on voltages and large forward currents compared to the traditionally grown device structure. The results lead to a better growth process for Ga2O3-based devices.