Quantum confined exciton states are analyzed from the absorption, luminescence and Raman spectra under hydrostatic pressure in SbI3 and BiI3 crystals. In SbI3, a new transition line series of excitons suddenly appears below the fundamental absorption edge under the pressure higher than ∼1.4 GPa. In BiI3, the similar line series appears even at atmospheric pressure. The energies of the lines converge to the low energy side revealing a feature of the quantum confinement. The pressure induced quantum confined states are discussed in terms of a phase transition of electronic structure due to the molecular rearrangement.
KEYWORDS:hydrostatic pressure, quantum confined state, exciton, stacking fault, BiI3, SbI3