Studies of surface passivation and new barrier height enhancement of n-type In0.53Ga0.47As Schottky barrier photodiodes have been carried out in this work. For surface passivation, various dielectric films such as Si02, Si3N4 and polyimide were studied and compared. The results showed that MSM photodiodes passivated with polyimide film yielded the lowest leakage current, whereas the Si02 passivated device had the highest leakage current. A new barrier height enhancement method on n- type In0.53Ga0.47As Schottky diodes was developed by depositing a thin graded superlattice of In0.53Ga0.47As/Ino.52A10.48As (10 periods, 60 Aper period) on n- In0.53Ga0.47As epilayer using MBE technique. Effective barrier heights of 0.71 and 0.60 eV were obtained for Au and Cr Schottky contacts deposited on this graded superlattice, respectively.
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