Electron and hole capture cross-sections at deep centers in gallium arsenide

Abstract

A method is presented, which combines optical excitation and electrical refilling of deep levels, allowing one to measure the majority carrier capture cross-section for minority carrier traps : e.g., σn for a hole trap in n-type material. This method has been used to characterize many deep levels in gallium arsenide. The following results are obtained : the main electron trap « EL 2 » is not a hole lifetime killer; the temperature coefficient of the ionization energy for several levels, including the Cr level used for compensation in semi-insulating crystals ; very large (10-15 cm 2 or more), and very small (10-21 cm2) electron capture cross-sections for two of the levels ; possible capture mechanisms for these last cases are mentioned