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

Abstract

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.