Anisotropic Complex Refractive Index Of Beta-Ga2o3 Bulk And Epilayer Evaluated By Terahertz Time-Domain Spectroscopy

Homoepitaxial film and semi-insulating bulk beta -Ga2O3 with (001) orientation were studied using terahertz time-domain spectroscopy (THz-TDS) in the frequency region from 0.2 to 3.0THz parallel to the [100] and [010] directions. The static permittivity of the bulk was determined to be 10.0 and 10.4 along thea-axis andb-axis, respectively, and the refractive index values at 0.2THz are 3.17 and 3.23 for each axis. The electrical resistivity of the epilayer was extracted with good accuracy by employing the Drude-Lorentz model and without the use of electrical contacts. This noninvasive and contact-free material evaluation through THz-TDS proves to be a powerful tool for probing and obtaining various types of information about beta -Ga2O3 materials such as bulk and thin films for the development of beta -Ga2O3-based device applications.