Determination of Gallium Concentration in Silicon from Low‐Temperature Photoluminescence Analysis

Abstract

Increasing our understanding of the electronic properties of gallium (Ga) in silicon (Si) used nowadays to manufacture p‐type Si solar cells is of key technological importance. In this contribution, the results of the effect of Ga concentration on the low‐temperature photoluminescence (PL) spectra in crystalline Si are reported. The Ga‐doped Si samples studied have negligible boron (B) concentrations, which can complicate spectral analysis of the bound exciton (BE) lines. We analyse the split Ga BE ground state at T = 10 K and compare the PL intensity ratios for the BE to free exciton (FE) peaks. By comparing these to known Ga concentrations, derived from capacitance‐voltage measurements, we establish an all‐optical (PL) calibration curve for the quantification of Ga concentration in Si. The effects of both temperature and excitation power on the PL intensity ratios are also studied. By combining the temperature‐induced changes in the PL intensity ratios with the calibration curve at 10 K, a calibration function has been determined. We found that the decay rates of the PL intensity ratios as a function of excitation power are independent of the chosen (split) BE peak. The major benefits of this method and its limitations are discussed.This article is protected by copyright. All rights reserved.