Deconvolution analysis of dopant depth profile of Si at AlGaAs/ GaAs interface using Al composition profile as reference

A novel method of deconvolution without using a reference sample was investigated for dopant depth profiling of Si in the AlGaAs/GaAs epilayers. The true Si distribution was numerically analyzed by deconvolution using a depth resolution function (DRF) obtained from an Al composition profile. The composition analysis by thickness fringe-transmission electron microscopy (CAT-TEM) revealed that the Al composition changed rapidly at the AlGaAs/GaAs interface and followed an ideal step function. The DRF of Al was, thus, derived by differentiating the measured Al profile. Deconvolution of the measured Si profile was performed by least-squares fitting of the convolved Si profile with the measured profile, under the assumption that a true Si distribution was in a Gaussian function. The variance s of the true distribution was found to be 1.9 nm after deconvolution. Simultaneously, decay length of the Si profile decreased by almost one-third compared to that before deconvolution. The deconvolved Si profile agreed well with the carrier profile of a high electron mobility transistor (HEMT). # 2004 Elsevier B.V. All rights reserved