Very large photogain and high photorespone linearity of Ge-dot photoMOSFETs operating in accumulation-mode for monolithic Si photonics

Abstract

We experimentally demonstrated that the inclusion of Ge dots into the gate stack of a Si MOSFET provides extremely high photoresponsivity over 1,000A/W and superior photoresponse linearity of at least 7 decades for 400–1300nm illumination, depending on whether the Ge-dot photoMOSFET operates in the inversion or accumulation modes. Remarkably a very large photocurrent gain of 103–108A/A and a significantly large dynamic range of photoresponse linearity with at least 6 decades for Pin = 6nW−1.376mW are concurrently achievable for our Ge-dot photoMOSFETs in the accumulation-mode operation thanks to extremely low dark current of 40pA. Photocarrier generation and recombination under high power illumination is analytically simulated.