Adrianna Wójcik
supervisor: Włodzimierz Strupiński
Precise and reliable determination of the spatial distribution of dopants in the structure as well as prediction of its temperature behavior is crucial for the practical applications of semiconductors. Standard dynamic Secondary Ion Mass Spectrometry (SIMS) provides depth profiles of impurity atoms without distinguishing electrically active and inactive parts. Whereas Electrochemical Capacitance-Voltage (ECV) technique yields depth profiles of all carriers present in the structure.
Recently, it has been demonstrated that using ultra-low impact energy SIMS (ULIE-SIMS) it is possible to access the qualitative distribution of impurity which is electrically active by measuring complex dopant-host signals. Furthermore, the ECV profiling shows a great promise to be a suitable tool for the calibration of ULIE-SIMS profiles.
This work presents the experiment designed to investigate the diffusion of electrically active and inactive impurities by complementary use of ECV and SIMS techniques. The initial ECV and SIMS experiments suggest that the total impurity distribution extends substantially deeper than its electrically active part. Si-doped GaAs layer of 500 nm thickness embedded between undoped GaAs layers will be subjected to thermal treatment at various temperatures. SIMS, ULIE-SIMS, and ECV measurements will be used to quantitatively determine the diffusion parameters of the active and total impurity giving a starting point for a discussion on the varying diffusion mechanism.