Silicon doped multiple quantum well (MQW) detector structures were rapid thermally processed (RTP) for the purpose of blue shifting the excitonic transition. Structures were encapsulated with Sio2 prior to the anneal as such enhanced the degree to which interdiffusion occurred within the structure. This further lead to a blue shift in the exciton energy corresponding to the n=l transition which was observed by photoluminescence (PL) measurements. Having examined the PL spectra of various SiO2 encapsulated samples and performing variable intensity PL measurements, a peak corresponding to a defect at ∼ 80meV above the valence band was further observed. In addition, a variation in the degree to which disordering occurs has been observed under various physical conditions including doping and GaAs capping.