High performance metal-insulator-semiconductor-insulator-metal photodetector fabricated on a silicon-on-oxide substrate

摘要

We demonstrate a planar metal-insulator-semiconductor-insulator-metal (MISIM) photodetector fabricated on a silicon-on-insulator substrate where the insulator is a stack of SiO2 and HfO2. The detector exhibits an extremely low dark current, as well as a large sensitivity and responsivity for wavelengths in the 365-880nm range. The current-voltage (I-V) characteristics under moderate illumination intensities are superlinear and saturate at high powers. This behavior is due to a space charge limited current mechanism, which causes a photocurrent amplification process. The current path through the detector is via filament sites induced by a voltage stress of the thermal SiO2 and HfO2 layers. These filaments allow for the internal photocurrent gain. Saturation of the I-V curves is caused by Schottky-type electrodes whose barrier height with silicon controls the thermionic emission of carriers through the filament sites to the silicon depletion region. At a bias of +/- 4V, we estimated a maximum sensitivity of 1.25x10(5), a responsivity of 68A/W, a detectivity of 6.5x10(13)Jones, and a quantum efficiency of 2.3x10(4)% of the photodetectors for an incident optical power of 0.143 mu W at 365nm wavelength.