Spectroscopic study of Ga-In-P based self-organized lateral superlattices

This paper reports polarization and temperature dependent contactless elect roreflectance (CER) and photoluminescence (PL) study of strain compensated short period (GaP)(2)(InP)(2) superlattices on GaAs(001) substrates which s how self-organized lateral composition modulation (LCM) in the form of alte rnate In/Ga rich regions along the [110] direction in the (001) plane. The LCM related PL peak position is at a lower energy as compared to the corres ponding feature in the CER spectrum and the difference is found to be the s ame as the activation energy for thermal quenching of the PL signal. These results have been explained by suggesting that the pi. signal arises mainly from recombination of carriers localized at potential fluctuations. (In ri ch regions with excessively high In concentration) within the lateral super lattice (LS) structure that is formed due to the LCM while the CER feature arises from transitions between the minibands of the average LS structure. The PL signal is quenched due to thermal excitation of the carriers from th ese excessively In rich regions into the minibands. The LS band gap energy is accurately determined and its implication for the random alloy model use d to describe the electronic band structure of such systems is discussed. T he temperature dependences of critical point energies have also been measur ed and analysed.