A new profiling technique applicable to the measurements sensitive to the free-carrier concentration rather than the depletion-layer thickness

A novel profiling procedure where the free-carrier concentration is the primary measured quantity is demonstrated. This method allows the depth profiling of the dopant concentration and other properties such as trap energy levels and generation lifetime by measurements monitoring such parameters as surface conductivity, surface photovoltage, reflectance, transverse acoustoelectric voltage (TAV), and Hall voltage. Nondestructive profiling is also possible by contactless methods, e.g., TAV measurements. The distinct difference between the pulsed capacitance-voltage (C-V) measurement and the proposed procedure is that in the former the measurable physical quantity is the depletion-layer width which is modulated by an external field. In the technique proposed here, the carrier concentration as a function of bias field is monitored and the depletion-layer width is then calculated. The theoretical analysis leading to the evaluation of the depletion width as a function of bias field is presented along with an experimental example, utilizing the nondestructive TAV measurement.