Résumé
AlGaAsSb/GaInAsSb heterojunction mesa photodiodes having 2.2µm cutoff wavelength, grown by MBE on (p) GaSb substrates, have been passivated using thioacetamide CH4CSNH2 and ammonium sulphide (NH4)2S. Superior characteristics were obtained from devices processed with thioacetamide in acid me-dium (pH = 2.4). At room temperature the surface leakage currents were suppressed, and the photodiodes showed R0A product as high as 15 Wcm2 and detectivity D*(2µm, 0V) ~ 1010 cm Hz1/2 W-1. A model ex-plaining improvement with thioacetamide is proposed.