Similar calculations can be applied to holes by replacing the electron effective mass m e ∗ ∗ with the hole effective mass m h ∗ ∗ . Introducing the total effective mass m t o t ∗ ∗ = m e ∗ ∗ + m h ∗ ∗ , the energy shift of the first optical transition induced by QCSE can be approximated to: