Raman study on H +-implantation effects in highly doped n-GaAs

Abstract

Vertical Bridgman grown, Si and B heavily doped n-GaAs (1 0 0) surface has been H +-implanted for various doses from 10 14 to 10 17 cm −2. The Raman spectra of A 1(LO) mode and LO phonon–plasmon coupled (LOPC) mode are recorded and analysed. Peak position (PP) of A 1(LO) mode increased up to 10 15 cm −2 dose due to the passivation effects and decreased at higher doses due to the implantation-induced lattice disorder whereas its full-width at half-maximum (FWHM) decreased at low doses and increased for higher doses for the same reasons. We report here, for the first time, the H +-implantation effects on LOPC mode. The peak position of LOPC mode decreased due to the passivation and the mode disappeared for a dose of 10 15 cm −2. For higher doses, the type conversion on the implanted layer occurred and the LOPC mode reappeared and its position increased with further doses. FWHM of LOPC mode increased with dose due to depth distribution of carrier concentration in the implanted layer. Area under A 1(LO) and LOPC modes increased with dose up to 10 15 cm −2 due to passivation effect resulting in increased scattering volume and decreased for higher doses due to the implantation-induced lattice disorder. Electron or hole carrier concentration in the implanted layer is estimated for various doses.