Improvement of electrical properties of GaAs on silicon by hydrogenation using plasma-enhanced chemical vapour deposition of hydrogenated silicon nitride

Abstract

We demonstrate the influence of hydrogenation on the electrical properties of GaAs on silicon heteroepitaxial layers. Hydrogenation is performed during the plasma-enhanced chemical vapour deposition of hydrogenated silicon nitride and post-annealing. Atomic hydrogen dissociated from hydrogen-containing active gases by a high electrical field can gain enough energy to penetrate into the GaAs layer and passivate the defect level and shallow donor level as well. Post-annealing treatments are applied to recover the shallow silicon dopants while keeping the deep levels passivated. We evaluated the efficiency of the defect passivation by photoluminescence (PL) tests and deep-level transient spectroscopy (DLTS). The PL tests show a significant peak increase as a consequence of the hydrogenation and lower defect levels are observed with DLTS. Improvement in electrical performance of Schottky diodes and metal-semiconductor field effect transistors after hydrogenation is presented. An excellent compatibility between the hydrogenation and the standard GaAs-on-silicon processing has been proven.