12.4 – EPD Is More Than a Number – Tackling Dislocation Density Assessment in Low Defect, Large Diameter GaAs and InP Wafer

Stefan Eichler, Freiberger Compound Materials GmbH
T. Milek, Freiberger Compound Materials GmbH
U. Kretzer, Freiberger Compound Materials GmbH
F. Borner
D. Deutsch, Freiberger Compound Materials GmbH

12.4 Final.2025

Abstract
Etch Pit Density (EPD) is a critical metric for assessing the quality of semiconductor wafers, providing insights into the density of dislocations and other crystal defects. The definition and measurement of robust and significant EPD evaluation parameters are essential for ensuring the performance, stability and cost efficiency of device manufacturing. In recent years the frontiers of low dislocation densities in VB/VGF grown GaAs and InP crystals have been pushed continuously. Traditional methods for EPD evaluation and assessment, while foundational, often fall short in addressing the complexities of modern semiconductor requirements. This paper will highlight the necessity of improving EPD counting and evaluation methods to meet the rigorous demands of contemporary semiconductor applications.