Raman study of Fano interference in p-type doped silicon

TL;DR

This study uses Raman spectroscopy across various wavelengths to investigate Fano interference effects in heavily p-type doped silicon, revealing electronic transitions and their relation to silicon's band structure for device insights.

Contribution

It provides new insights into Fano interference in doped silicon by analyzing the electronic transitions and their impact on Raman lineshape asymmetry across a broad wavelength range.

Findings

Identification of electronic transition above and below 3.4 eV in silicon

Correlation between band structure anisotropy and penetration depth

Observation of Fano interference affecting Raman lineshape

Abstract

As the silicon industry continues to push the limits of device dimensions, tools such as Raman spectroscopy are ideal to analyze and characterize the doped silicon channels. The effect of inter-valence band transitions on the zone center optical phonon in heavily p-type doped silicon is studied by Raman spectroscopy for a wide range of excitation wavelengths extending from the red (632.8 nm) into the ultra-violet (325 nm). The asymmetry in the one-phonon Raman lineshape is attributed to a Fano interference involving the overlap of a continuum of electronic excitations with a discrete phonon state. We identify a transition above and below the one-dimensional critical point (E = 3.4 eV) in the electronic excitation spectrum of silicon. The relationship between the anisotropic silicon band structure and the penetration depth is discussed in the context of possible device applications.