EFFECT OF HYDROGENATION ON THE PHOTOLUMINESCENCE OF GAAS ALGAAS QUANTUM-WELL STRUCTURES/

A study has been made of how treatment in the plasma of a hydrogen glo w discharge affects the photoluminescence of test samples of several t ypes at a temperature of 78 K. The samples were layers of several comp ositions grown by vapor-phase epitaxy from metal-organic compounds. Th e layers consisted of undoped Al0.3Ga0.7As; silicon-doped Al0.28Ga0.72 As (n approximately 10(17) cm-3); undoped GaAs; undoped multilayer str uctures with several GaAs/Al0.23 Ga0.77As quantum wells, with widths o f 2, 3.6, 5.4, and 23 nm; and undoped GaAs/AlGaAs double heterostructu res with separate electronic and optical confinement with a 20-nm acti ve region. The hydrogenation reduces the photoluminescence intensity o f undoped Al0.3Ga0.7As and GaAs layers, while it intensifies this lumi nescence in the case of silicon-doped Al0.28Ga0.72As. The photolumines cence intensity of GaAs/AlGaAs quantum wells is increased sharply by t he treatment in a hydrogen plasma. The observed effect is seen most vi vidly in the case of narrow quantum wells. It stems from a passivation by hydrogen of radiationless defects at heterojunctions. After hydrog enation of a double heterostructure with separate confinement containi ng transition layers with a composition gradient near the heterojuncti ons, the photoluminescence spectrum of the GaAs active region becomes sharply narrower.