Comparison of E-beam and Sputter-Deposited ITO Films for 1.55 um Metal- Semiconductor-Metal Photo-Detector Applications

摘要

The optical and electrical properties and surface morphology of sputtered, e-beam deposited and composite e-beam/sputtered ITO films for Metal-Semiconductor-Metal (MSM) photo-detector applications were compared. The resistivity of sputtered ITO was almost two-orders of magnitude less than that of e-beam deposited ITO, while the resistivity of the composite films was only 15% higher than that of sputtered films. The transmittance at 1.55 μm of sputtered and composite ITO films was 83% and 77% respectively, which was much higher than the value of 13% for the e-beam deposited ITO. The composition of ITO films for both deposition techniques was very similar, as determined from with Auger Electron Spectroscopy surface scans and depth profiles. The sputtered films showed much smoother surfaces and smaller grain size. InGaAs Based MSM devices with ITO fingers have been fabricated and showed higher photo response than that of MSM devices with conventional Ti/Au fingers.