Temperature Dependence of X₁-X₃ Splitting Energy in Lightly Doped GaP

Abstract

The splitting energy δ between the X1-band with an effective mass m 1 * and the X3-band with m 2 *, and the effective mass ratio m 2 */m 1 * for the conduction band of n-GaP were determined as a function of the temperature T by measuring the infrared absorption and fitting theoretical curves of the X1→X3 absorption band. As T rises, δ decreases as 0.349-6.83×10-5 T 2/(T+460) [eV], which can be explained by a faster shift of the upper X3-band than the lower X1-band toward the valence band. This empirical equation gives δ=0.316 eV at 773 K. The m 2 */m 1 * increases, which indicates that the upward-bending of the X1-band has a stronger T-dependence than the X3-band.