A new method using the Hall technique to determine the change in surface layer thickness of doped semiconductors is presented. An equation to calculate the semiconductor thickness change has been determined by comparing the difference in Hall measured sheet carrier concentration and mobility before and after a change in surface layer thickness. Experiments were conducted using a wet chemical digital etch to removen-type GaAs surface layers having an incremental etch depth control of approximately 15 Å in thickness, and the resulting thickness changes were calculated by the Hall technique and measured with a mechanical profilometer. This Hall measurement technique was able to measure changes in surface layer thickness of less than 100 Å, and the accuracy of this new technique compared favorably with mechanical profilometer measurements. The new Hall technique method provides accurate measurements of minute thickness changes, and is more accurate than mechanical profilometers for thickness changes less than 150 Å.©1997 American Institute of Physics