Polymer-Based MEMS Photodetector With Spectral Response in UV-Vis-NIR and Mid-IR Region

Integrating various components on the same chip is highly sought after for various optoelectronic applications. In an attempt to provide an on-chip photodetection, a MEMS-based photodetector device with a wide spectral response is presented. The design merges the photoconductive and pyroelectric properties of nanomorphology-controlled polyvinyl alcohol as a photoactive layer. The fabrication technology is low cost with a single-layer deposition of photoactive polymer on a MEMS low thermal mass platform designed to improve the heat loss to the substrate. This fabricated device with a metal-semiconductor-metal structure shows Schottky diode behavior. The photoresponse of this device was observed from UV to mid-IR region with minimum light detection capability of 30 nW in UV, 120 nW for visible light, and 100 mu W for IR light. The effect of nanomorphology and the thickness of the photoactive layer were studied to optimize the responsivity in the different waveband regions. Typically, at zero bias, under 405-nm illumination with light intensity of 170 mu W/cm(2), the photodetector exhibited responsivity of 0.53 A/W. The wavelength response of this detector was found to be similar with standard detectors of the UV visible as well as mid-IR region (6.3-10.6 mu m). The proposed on-chip MEMS-based photodetection module with the broad-spectrum detection capability and lower power consumption is useful for lab-on-chip-based technologies for a wide range of optical/spectroscopic applications.