Structural modification in reactive-ion-etched i-InP and n⁺-InP studied by Raman scattering

Structural and electrical property modifications in i-InP and n ⁺-InP by reactive ion etching have been characterized by using Raman scattering to observe changes in the positions and intensities of intrinsic phonons and coupled phonon-plasmon bands. Different etch gas compositions (Ar, He, CH₄/H₂, CH₄/Ar, CH₄/He, and CH₄/H₂/Ar), bias potentials (0-500 V), and etch times were examined. Electrical property changes were followed by correlating results with a one-sided abrupt junction model. Ar and He, which interact with the material by physical sputtering processes, were found to induce the greatest structural and electrical modifications. Ar-etched samples exhibited the greatest structural modification, with evidence of structural damage coming from far beyond the calculated penetration depth of low-energy Ar⁺, while samples etched in methane-based plasmas showed very little structural perturbation. Etching in all of the gas mixtures used produced some degree of electrical modification in n⁺-InP, with He plasmas causing the most significant changes. In general, samples etched with lower ion energies and sputter components exhibited the least structural and electrical modification.