PREPARATION AND CHARACTERIZATION OF TA2O5 TA/SI SCHOTTKY PHOTODIODE STRUCTURES/

Low ion energy (200 eV Ar+) rf magnetron sputter etching of the Si sub strate and Ta sputter deposition are applied for the preparation of Ta /Si Schottky photodiode structures. An appropriate thermal annealing a t 430-degrees-C for 30 min in dry air is used for the partial oxidizat ion of the Ta layer. The Ta2O5 layer shows specific passivating and pa rtially antireflection properties. The XPS characterization reveals th e sequence, the thickness, and the chemical composition of the structu re components. The metal/semiconductor interface is abrupt and does no t show any chemical reactions as a result of the thermal treatment. Th e SB height is 0.7 and 0.73 eV as derived from the I- U and C- U measu rements, respectively. The SB ideality factor amounts to 1.08 to 1. 11 and the reverse current density is about 10(-5) A/cm2. The photodiode structures are sensitive in the (0.5 to 1.05) mum range with a maximu m static sensitivity of 0.15 A/W.