Growth and Characterization of Semi-Insulating GaAs for Use in Ion Implantation

Abstract

A review of semi-insulating GaAs produced by three current bulk growth technologies has been made in which the electrical properties of the resultant semi-insulating GaAs have been studied in detail. High resistivity GaAs grown by liquid encapsulated Czochralski techniques is contrasted with horizontal Bridgman and gradient freeze materials. Both undoped and chromium-compensated materials have been studied. Materials qualification for ion implantation as determined by measurement of resistivity, thermal stability and active ion implant distributions will be described. Degree of impurity activation and relationship to LSS range statistics are discussed for selenium ion implants. Assessment of deep centres with concentration <10¹⁴ cm^-3 have been made on high resistivity samples using photo-induced current transient and dark conductivity versus temperature measurements. Impurity redistribution effects resulting from thermal annealing with Si₃N₄ capping layers are assessed by analysis with secondary ion mass spectroscopy (SIMS). Conclusions drawn from qualification tests, electrical transport and mass spectrographs measurements are correlated with the specific materials growth method used.