Low-noise, high-detectivity, polarization-sensitive, room-temperature infrared photodetectors based on Ge quantum dot-decorated Si-on-insulator nanowire field-effect transistors
J. John, Veerendra Dhyani, Sudarshan Singh, Alka Jakhar, Arijit Sarkar, Samaresh Das, S. K. Ray
Abstract
Abstract A CMOS-compatible infrared (IR; 1200–1700 nm) detector based on Ge quantum dots (QDs) decorated on a single Si-nanowire channel on a silicon-on-insulator (SOI) platform with a superior detectivity at room temperature is presented. The spectral response of a single nanowire device measured in a back-gated field-effect transistor geometry displays a very high value of peak detectivity ∼9.33 × 10 11 Jones at ∼1500 nm with a relatively low dark current (∼20 pA), which is attributed to the fully depleted Si nanowire channel on SOI substrates. The noise power spectrum of the devices exhibits a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1</mml:mn> <mml:mo>/</mml:mo> <mml:msup> <mml:mrow> <mml:mi>f</mml:mi> </mml:mrow> <mml:mi>γ</mml:mi> </mml:msup> <mml:mo>,</mml:mo> </mml:math> with the exponent, γ showing two different values of 0.9 and 1.8 owing to mobility fluctuations and generation-recombination of carriers, respectively. Ge QD-decorated nanowire devices exhibit a novel polarization anisotropy with a remarkably high photoconductive gain of ∼10 4 . The superior performance of a Ge QDs/Si nanowire phototransistor in IR wavelengths is potentially attractive to integrate electro-optical devices into Si for on-chip optical communications.