Raman Scattering Characterization and Electron Phonon Coupling Strength for MeV implanted InP(111)

TL;DR

This study uses Raman spectroscopy to analyze structural damage, phonon behavior, and electron-phonon coupling in InP(111) after MeV Sb implantation, revealing phase transitions, stress, and nano-crystalline formation.

Contribution

It provides a detailed Raman-based analysis of lattice modifications, phonon confinement, and electron-phonon coupling in InP(111) post high-energy ion implantation, highlighting phase transition and nano-crystalline effects.

Findings

Damage increases with fluence, affecting phonon modes.

Presence of charge layer influences Raman spectra.

Electron-phonon coupling decreases with smaller nano-crystals.

Abstract

Structural modifications in InP(111) due to 1.5 MeV implantation of Sb have been characterized using first order and second order Raman spectroscopy. With both Longitudinal Optical (LO) and Transverse Optical (TO) modes allowed for InP(111), we have investigated the evolution of both these modes as a function of fluence. Intensity, linewidth and shifts of the phonons, for both first order and second order Raman modes, display the increase in damage in the lattice with increasing fluence. The results suggest that the presence of a charge layer in the vicinity of the surface may be effecting the first order Raman data. A LO phonon-plasmon coupled mode, due to the charge layer, has also been observed that becomes sharper and more intense with increasing fluence. Results also show the presence of tensile stress along with the coexistence of crystalline InP regions and amorphous zones in the lattice. Consequently phonon confinement is observed. Phonon Confinement model (PCM) has been applied here to estimate the coherence length and the size of nano-crystalline zones in InP lattice after implantation. A crystalline/ amorphous (c/a) phase transition is observed at the fluence of $1\times10^{14} ions/cm^{2}$. The electron-phonon coupling strength has been measured by utilizing the second order Raman modes. This coupling strength is seen to decrease as the nano-crystalline zones, in the implanted lattice, become smaller.