Photoluminescence study of residual shallow acceptors in liquid-encapsulated Czochralski-grown InP

For nominally undoped InP crystals grown in silica, pBN, ceramic AlN, and pG crucibles by the liquid-encapsulated Czochralski (LEC) technique, residual shallow acceptors are investigated by photoluminescence measurements. Mg and Ca, contained in the InP starting materials, are found to be removed due to reactions with the B2O3 encapsulant. Zn and C, of which Zn was dominant throughout the undoped crystals, are found to be residual acceptors incorporated during LEC growth. The B2O3 encapsulant is identified as one Zn contamination source.