Photoluminescence of Low-Energy B+-Implanted Silicon under Ultraviolet Light Excitation

Abstract

We measured photoluminescence (PL) spectra of Si implanted with 0.5 keV B+ ions to doses varying from 1.0×1014 to 4.0×1015 cm-2. We compared the PL spectra under ultraviolet (UV) light (the 351 and 364 nm lines of an Ar ion laser) excitation with those under visible light (the 488 nm line of an Ar ion laser) excitation. The emission due to the impurity band of B was observed only in the case of the UV light excitation, indicating that the activated B atoms were located in the shallow region of the order of 10 nm. The I1 line at 1.02 eV and the broad band consisting of two bands with peaks at 0.82 and 0.97 eV were also observed in the PL spectra. They are related to different types of point defect clusters. Comparing the PL spectra under different light excitations, we conclude that the distribution of the defects induced by ion implantation is not restricted in the shallow region of the implanted B atoms even in the as-implanted sample. We also conclude that the 0.97 eV defect extends to the region deeper than the region of the 0.82 eV defect after the annealing.