IN-VACUUM CLEAVING AND COATING OF SEMICONDUCTOR-LASER FACETS USING THIN SILICON AND A DIELECTRIC

We propose and demonstrate a novel approach to the coating of semicond uctor laser facets. In this approach, processed semiconductor lasers a re cleaved in a high-vacuum system immediately followed by coating of the vacuum-exposed facet with a very thin Si layer (less than or equal to 100 Angstrom) and a large band gap dielectric (Al2O3) layer. The S i layer is sufficiently thin to avoid the formation of quantized bound states in the Si. GaAs coated with thin Si and Al2O3 have a higher lu minescence yield and a lower surface recombination velocity than bare GaAs surfaces as well as GaAs surfaces coated with Al2O3 only. A surfa ce recombination velocity of 3x10(4) cm/s has been obtained using a mo dified dead layer model for the Si/Al2O3 sample. It is also shown that lasers which are cleaved in vacuum and subsequently coated with Si an d Al2O3 have improved properties including an increased threshold for catastrophic optical damage. (C) 1996 American Institute of Physics.