Spectroscopic ellipsometry characterization of boron nitride films synthesized by a reactive plasma-assisted coating method

Abstract

The optical constants of boron nitride (BN) films on Si substrates were systematically investigated using spectroscopic ellipsometry. BN films with a wide variety of atomic compositions (B/N ratios) and bonding phases (sp2/sp3 ratios) were synthesized using a reactive plasma-assisted coating method, which consists of magnetically confined vacuum-arc discharge and electron-beam evaporation. A wide range of optical constants were assigned to various BN films via a model fitting procedure employing the Tauc–Lorentz optical model. The estimated film thicknesses corresponded with those determined using scanning electron microscopy. The optical constants of the films were found to be significantly dependent on their respective atomic compositions, which shows a transition from the semiconducting to the insulating phase in BN films in response to the deposition conditions. Ion bombardment during the film growth induced an increase in the refractive index along with an increase in the amount of the sp3 phase. Furthermore, the extinction coefficient increased substantially in the ultraviolet region in response to the generation of defects in the BN nano-network structures.

Ion irradiation-induced sputtering and surface modification of BN films prepared by a reactive plasma-assisted coating technique

“…Spectroscopic ellipsometry 106,107) was employed to analyze the surface sputtering depth. The optical thickness d BN was determined using a Tauc-Lorentz optical model 108) for various BN films and the obtained thickness was found to be in good agreement with the physical thickness identified by scanning electron microscope (SEM) observations. The thickness change before and after plasma exposure was To further identify the phase change in the plasmairradiated region, FTIR, nanoindentation, and electrical analyses were performed.…”

Polytypes of sp2-Bonded Boron Nitride

“…This simple description of the effect of a uniaxial strain inside a BN layer does not explain reasonably the qualitative differences observed in the experimental curves of the dielectric constant plotted in Figure 6. Recent ellipsometry measurements recorded worldwide at room temperature confirm a broad reflectivity feature near the value of the fundamental bandgap [71] with some puzzling discrepancies attributed to differing amounts of hBN and turbostratic BN, and/or the co-existence of sp 2 and sp 3 -bonded crystallites [118].…”

Optical and electrical evaluation methods of plasma-induced damage in InP substrates

“…T-L model is considered to be versatile, i.e., applicable for a wide variety of PPD characterization of dielectric films. 39) Using the T-L model, the dielectric function for IL and the thickness d IL are determined with six fitting parameters including d IL . In the EMA model, the dielectric functions are defined as the composition of an oxide and bulk material (substrate).…”