PROCEEDINGS ARTICLE | May 31, 2007
Proc. SPIE. 6585, Optical Sensing Technology and Applications
KEYWORDS: Photodetectors, Argon, Electrodes, Gases, Oxygen, Transmittance, Palladium, Plasma, Tin, Absorption
The RF-sputtered ITO layers were used as the transparency contact layer of the MSM PDs. The plasma gas would alter
the optical transmittance and the schottky barrier height between the ITO layer and InGaAsN absorption layer. Three
kinds of plasma gases were studied including Ar, Ar/N2, and Ar/O2. The Schottky barrier heights were 0.510 eV, 0.572
eV, and 0.574 eV when using Ar, (Ar/N2), and (Ar/O2) as the plasma gas; besides, the optical transmittances were
92.56%, 93.12% and 96%, respectively. Although the ITO film sputtered in the Ar/O2 ambient has highest transmittance
and Schottky barrier height, the high resistivity limited the photocurrent of the photodetectors; it is almost three orders
lower than the others. Consequently, using the Ar/N2 as the plasma gas would be a suitable choice regarding the MSM
photodetector application. The highest contrast ratio between photo-current and dark-current of the InGaAsN MSM
photodetectors were 5, 25 and 12 (measured under 0.2V) using Ar, Ar/N2, and Ar/O2 as the plasma gases.
