SIMS analysis of a multiple quantum well structure in a vertical cavity surface emitting laser using the mixing-roughness-information depth model

We have analyzed a multiple quantum well (MQW) structure in a vertical cavity surface emitting laser (VCSEL) epitaxial wafer using secondary ion mass spectrometry (SIMS). The two energy sputtering method is a very powerful method for providing a depth profile of a GaAs/ Al0.2Ga0.8As MQW with a sufficient depth resolution and a large number of data points in a practical measurement time. This method consists of rapid high-energy sputtering for a top mirror layer and subsequent low-energy sputtering for an active layer. The resulting profiles were quantitatively evaluated using the mixing-roughness-information depth (MRI) model. The values of C concentration in modulation-doped Al0.2Ga0.8As barrier layers have been extracted from the original in-depth concentration profile reconstructed by the MRI model. The relationship between depth resolution of the resulting profile and surface morphology measured by atomic force microscopy (AFM) is also discussed.