Matrix Effect Quantification for Positive SIMS Depth Profiling of Dopants in InP/InGaAsP/InGaAs Epitaxial Heterostructures

Abstract

Quantitative depth profiling of a single dopant through an optoelectronic heterostructure wafer requires a reference standard of that dopant in each layer composition encountered, typically InP, In0.53Ga0.47As, and one or more lattice-matched quaternary alloy compositions Inl−yGayAsxP1−x.1 This matrix calibration problem has previously been addressed by GALUSKA AND MORRISON [1] and MEYER et al. [2] for the AlxGal−xAs/GaAs heterostructure system. Significantly larger positive secondary ion yields of various dopants were obtained from AlxGa1−xAs relative to GaAs, with relative yield increasing linearly with Al content. In this work we have prepared by ion implantation standards of five technologically important dopants (Be, Mg, Si, Zn and Sn) in InP, InGaAs and an InGaAsP layer of approximately equal As and P content. Dopant profiles were determined by positive SIMS employing a reactive O2 + primary beam for enhancement of the positive ion yield. Relative secondary ion yields of each dopant in the three matrices are presented, in each case for two different secondary ion energies. In addition, sputtering rates and yields of the three host matrices have been determined. Use of the relative secondary ion and sputtering yields permits conversion of the SIMS raw data into a true depth profile in the heterostructure [3], and prevents serious misinterpretation of uncorrected profiles.