Noninvasive and Contactless Characterization of Electronic Properties at the Semiconductor/Dielectric Interface Using Optical Second-Harmonic Generation

Abstract

Optical second-harmonic generation (SHG) is a reliable technique for probing material surface and interface characteristics. Here, we have demonstrated a non-destructive, contactless SHG-based semiconductor/dielectric interface characterization method to measure the conduction band offset and quantitatively evaluate charge densities at the interface in oxide and at the oxide surface. This technique extracts the interface-trapped charge type (donor/acceptor) and qualitatively analyzes the process-induced variation in interface states (D it ), oxide, and oxide surface state density. These qualitative and quantitative analyses provide us with a glimpse into the band bending. The metrology method is validated through a detailed characterization of the Si/HfO 2 interface. An optical setup has been developed to monitor the time-dependent second-harmonic generation (TDSHG) from the semiconductor/oxide interface. The temporal characteristics of TDSHG are explained with its relationship to the filling of D it and spatio-temporal trapping of photoexcited charge in oxide and at the oxide surface. A numerical solver, based on plausible carrier dynamics, is used to model the experimental data and to extract the electronic properties at the Si/HfO 2 interface.

Optical Second Harmonic Generation of Low-Dimensional Semiconductor Materials

“…The primary characteristics of this technique include its superior phase stability and sensitivity, coupled with relatively brief data acquisition periods. Optical SHG is also a reliable, non-destructive, and contactless technique for probing charge densities of the semiconductor/dielectric interface [ 216 ]. This optical method provides a new method for simple and effective measurement that can be used to characterize semiconductor interfaces in detail and to simulate experimental data using numerical solvers to extract the electronic properties of semiconductor interfaces.…”

The study of interface quality in HfO2/Si films probed by second harmonic generation

“…In another study, the detailed characterizations of interface state density at the HfO 2 /Si film were conducted by the SHG technique. These qualitative/quantitative evaluations provide the details about energy band bending at the HfO 2 /Si interface [18]. Therefore, the TD-SHG should be a promising method to efficiently characterize the defects and interface state density in the dielectric/semiconductor structures.…”